Bug in UCDialplans North American Rulesets

I was troubleshooting an issue where people couldn't dial US/CA toll-free numbers in Teams the other day, when using Direct Routing. Initially, the root issue wasn't that easy to solve, due to the lack of a Voice Routing Test Case tester like we have in Skype for Business. Normally, one of the first things I do when troubleshooting issues like this, is to make sure the user is actually ALLOWED to make such phone calls, based on their assigned voice policy. Teams doesn't have an equivalent to the SfB voice route tester. If it did, I would have found it much sooner.

The first thing that I did was look at the user's call history in the Teams Admin Centre. Sure enough, every toll-free call made by the user failed with the below error logged in Teams:

"The destination failed because it doesn't exist"

No information about this error came up in a search. Reviewing logs from the SBC showed the call never got to the SBC. Client logs didn't provide any usable information. Finally, I looked deeper into the applied dialplan. At this point, I saw the problem, and it was me.

Of course, I had applied a ruleset generated by UCDialplans.com. Everybody was automatically assigned the global voice policy, which was set to allow dialing only within the US. This utilizes a feature in UCDialplans.com where you can decide exactly what constitutes a "National" call.

If you're not familiar with the intricacies of the North American dialplan (NANPA), just know that the US, Canada and 26 Caribbean countries share the country code +1.  Each country has its own set of one or more area codes. There is no way to distinguish whether a number is in the US, Canada or a Caribbean country just by looking at it.

UCDialplans.com can configure your National voice policy so that a "National" call can include any number that starts with +1, limit to US/CA or limit it to US OR CA. When creating the ruleset, UCDialplans.com has a drop-down option where you decide what you want to "Treat as National".

If you select "In-Country Only" (which is the default option), UCDialplans.com will create a national voice route that only includes the area codes for the selected country. The current US example is below, which explicitly details every area code in the US, and is derived programmatically from the current list of area codes:

^\+1(?!(900|976))(20[^04]|21[^1]|22[^1267]|23[149]|24[08]|25[12346]|26[0279]|27[0269]|30[^06]|31[^1]|32[0135]|33[^358]|34[0167]|35[12]|36[014]|38[056]|40[^03]|41[^168]|42[345]|43[0245]|44[0235]|46[39]|47[0589]|48[04]|50[^06]|51[^149]|53[0149]|54[01]|55[19]|56[12347]|57[01345]|58[056]|60[^04]|61[^13]|62[03689]|63[016]|64[016]|65[017]|66[01279]|67[018]|68[0124]|70[^059]|71[^01]|72[04567]|73[1247]|74[037]|75[47]|76[02359]|77[^1678]|78[1567]|80[^079]|81[^19]|83[0128]|84[3578]|85[^1235]|86[02345]|87[028]|90[^025]|91[^1]|92[0589]|93[^235]|94[0179]|95[12469]|97[^4567]|98[0459]|281|458|520|828)[2-9]\d{6}

For the US/Canada option, rather than explicitly including every area code, it EXCLUDES Caribbean area codes, which is a much smaller list. Similarly, for US/Canada/Caribbean there is no need to exclude any area code (except premium), so the list is even smaller.

In an effort to reduce route selection time and processing overhead, the National voice policy doesn't explicitly include PSTN usages for local dialing, UNLESS least-cost routing is being used. For the US/Canada and US/Canada/Caribbean route options, toll-free numbers are captured by the route pattern because they're NOT in the exclusion list of Caribbean area codes. Unfortunately, I didn't account for toll-free numbers in the US or Canada Only route options, which means that toll-free numbers can't be dialed if you use the default options.

You could fix this by adding the Local PSTN usage to your voice policies, but that adds unnecessary overhead. A better option is to explicitly include toll-free numbers in the computed route.

^\+1(?!(900|976))(20[^04]|21[^1]|22[^1267]|23[149]|24[08]|25[12346]|26[0279]|27[0269]|30[^06]|31[^1]|32[0135]|33[^358]|34[0167]|35[12]|36[014]|38[056]|40[^03]|41[^168]|42[345]|43[0245]|44[0235]|46[39]|47[0589]|48[04]|50[^06]|51[^149]|53[0149]|54[01]|55[19]|56[12347]|57[01345]|58[056]|60[^04]|61[^13]|62[03689]|63[016]|64[016]|65[017]|66[01279]|67[018]|68[0124]|70[^059]|71[^01]|72[04567]|73[1247]|74[037]|75[47]|76[02359]|77[^1678]|78[1567]|80[^079]|81[^19]|83[0128]|84[3578]|85[^1235]|86[02345]|87[028]|90[^025]|91[^1]|92[0589]|93[^235]|94[0179]|95[12469]|97[^4567]|98[0459]|281|458|520|828|8(00|33|44|55|66|77|88))[2-9]\d{6}

The latest version of UCDialplans.com does this now, but if you've previously applied a UCDialplans.com ruleset using the "In-Country Only" option, you can either manually update your National voice route, or you can run one of the below scripts, which will seek out any US/CA-National voice route and apply the fix. If you use any of the other options, you aren't affected.

How can I tell which option was used?

Easily. The voice route for either of the other options are MUCH smaller in size. If your voice routes look like this, you are not affected.

US/Canada: (?!(24[26]|26[48]|284|345|441|473|649|664|721|[67]58|767|784|8[024]9|86[89]|876|900|976))[2-9]\d\d[2-9]\d{6}

US/Canada/Caribbean: (?!(900|976))[2-9]\d\d[2-9]\d{6}

The Fix is In

The below PS commands will append tollfree prefixes to the problematic voice route. Run whichever is appropriate for your environment, and BACKUP before you run this.

Skype for Business Fix

$Routes = Get-CsVoiceRoute | Where {($_.Identity -eq 'US-National' -or $_.Identity -eq 'CA-National') -and $_.NumberPattern -notlike '*[2-9]\d\d[2-9]\d{6}' -and $_.NumberPattern -notlike '*8(00|33|44|55|66|77|88)*'}; ForEach ($Route in $Routes) {Set-CsVoiceRoute -Identity $Route.Identity -NumberPattern $Route.NumberPattern.replace(")[2-9]\d{6}","|8(00|33|44|55|66|77|88))[2-9]\d{6}")}

Microsoft Teams Fix

$Routes = Get-CsOnlineVoiceRoute | Where {($_.Identity -eq 'US-National' -or $_.Identity -eq 'CA-National') -and $_.NumberPattern -notlike '*[2-9]\d\d[2-9]\d{6}' -and $_.NumberPattern -notlike '*8(00|33|44|55|66|77|88)*'}; ForEach ($Route in $Routes) {Set-CsOnlineVoiceRoute -Identity $Route.Identity -NumberPattern $Route.NumberPattern.replace(")[2-9]\d{6}","|8(00|33|44|55|66|77|88))[2-9]\d{6}")}


My apologies to anyone caught up by this bug. If you see me in the streets, feel free to slap me.

North American Call Authorization Tricks

Almost every country in the world has a dedicated country code assigned to it for telephony purposes (see countrycode.org for a full list). There is one very large exception to this rule and that is countries in North America (US and Canada) and a good portion of the Caribbean.  These countries all share the same country code of +1 and are collectively part of the North American Numbering Plan (NANP), which is managed by the North American Numbering Plan Association (NANPA).

A NANP number consists of the country code +1, a 3-digit area code, and a 7-digit subscriber number, often formatted like +1 (212) 222-3333.  You'll sometimes see the +1 omitted from the number on business cards and websites that don't think globally.

Dialing numbers in North America is quite different from most places in the world.  In the rest of the world, if you want to dial a long-distance or national number, you have to dial a national access code.  In a lot of countries, this number is 0.  However, in NANP countries, you have to dial 1 for long-distance/national numbers. That's right, you have to dial the actual NANP country code as the long-distance access code, which is unique among all other countries.  Incidentally, the international access code is 011 (in many other countries, its 00).

"Connect me with the German Chancellor immediately! I have an idea for a new album!"

If you want to dial Canada from the US, or the US from Canada, or any of the Caribbean countries in NANP, you don't dial the international access code 011, you just dial the number as you would any other long-distance number.  So, if I want to dial Toronto, Canada from Vancouver, Canada I would dial +1 416 555 1111.  If I wanted to dial New York City from Vancouver, I'd dial +1 212 555 1111.

It gets even better.  NANP area codes are allocated by a trio of over-caffeinated spider monkeys who press numbers on a giant keypad at random to assign a new area code (well, that's how it appears).  There is no logical separation between area codes between any of the countries.  For example, area code 646 is in New York, USA, 647 is in Ontario, Canada, and 649 is in the Turks & Caicos (Caribbean island nation). Click here for a current list of area code allocations in NANP.

These days, calls between the US and Canada are often priced identically to a domestic long-distance call.  But calls to the NANP Caribbean countries are usually priced much higher, akin to dialing some very remote international destinations.  Continuing the previous example, a US user that has signed up for Microsoft's Skype for Business Online PSTN Calling Plan can expect to pay $0.013 per minute  (just over 1 cent a minute) to call area code 647 in Ontario, but would end up paying $0.583 (almost 45x more expensive) to $0.741 per minute to call area code 649 in the Turks & Caicos.

Since it is nigh impossible for a regular person to distinguish a Caribbean country from US/Canada based solely on the area code, it is easy for people to accidentally incur high phone charges when calling these countries.

He had an Apple watch long before anybody else. True trendsetter, even if it took 30 years.

Skype for Business administrators often want to prevent certain users from dialing these Caribbean countries, and it can be easily done with some fancy routing rules.  Assuming you've already configured voice polices for national and international access, then you just have to modify the National level voice route to block Caribbean destinations.  You could do some research to determine the Caribbean area codes, and create your own regular expression to block them, but I figure I should do SOMETHING useful with this post and provide you with that information.

This Skype for Business route number pattern will block all Caribbean countries that are part of NANP, except for the US Virgin Islands and Puerto Rico (which are often not priced much differently than US numbers, when calling from the US):

\+1(?!(24[26]|26[48]|284|345|441|473|649|664|721|758|767|784|8[024]9|86[89]|876|900|976))[2-9]\d\d[2-9]\d{6}$

If you want to also block US Virgin Islands and Puerto Rico, then use this one:

^\+1(?!(24[26]|26[48]|284|34[05]|441|473|649|664|721|758|767|78[47]|8[024]9|86[89]|876|900|939|976))[2-9]\d\d[2-9]\d{6}$

You may note that I've also made sure to exclude premium area codes like 900 and 976.

To make sure that people assigned an International voice policy can dial those Caribbean countries, your international route should include a pattern for North American numbers and look something like this:

^\+((1(?!(900|976))[2-9]\d\d[2-9]\d{6})|([2-9]\d{6,14}))$

If you REALLY wanted to get draconian and block calls to Canada from the US, and vice versa, you could use the following rules:

Block Canadian and Caribbean calls:

^\+1(?!(900|976))(20[^04]|21[^1]|22[4589]|23[149]|24[08]|25[12346]|26[0279]|27[026]|30[^06]|31[^1]|32[0135]|33[^2358]|34[067]|35[12]|36[01]|38[056]|40[^03]|41[^168]|42[345]|43[0245]|44[023]|47[0589]|48[04]|50[^06]|51[^149]|53[0149]|54[01]|55[19]|56[12347]|57[01345]|58[056]|60[^04]|61[^13]|62[03689]|63[016]|64[16]|65[017]|66[01279]|67[018]|68[124]|70[^059]|71[^01]|72[0457]|73[1247]|74[037]|75[47]|76[02359]|77[^1678]|78[1567]|80[^079]|81[^19]|83[012]|84[3578]|85[^1235]|86[02345]|87[028]|90[^025]|91[^1]|92[0589]|93[16789]|94[0179]|95[12469]|97[^4567]|98[0459]|281|458|469|520|828)[2-9]\d{6}$

Block American and Caribbean calls:

^\+1(?!(900|976))(41[68]|43[178]|51[49]|58[17]|70[59]|78[02]|90[25]|204|226|236|249|250|289|306|343|365|403|450|506|548|579|604|613|639|647|778|807|819|825|867|873)[2-9]\d{6}$

The above rules are formatted slightly differently from the ones that block Caribbean countries.  The Caribbean rules show which area codes to BLOCK.  The other rules show which area codes to ALLOW.  Of course, I didn't roll these rules by hand, since there are tens of dozens of area codes allocated to each country, and do change from time to time.   I used the super handy-dandy Lync Optimizer.  As you might expect, these options are available in the Lync Optimizer via the "Treat as National" option (only shows for North American dial rules).  You can select one of the following options with regards to dialing other countries within NANP:

1. In-Country Only - Treat all calls to NANP countries other than your own as international, even though users don't have to dial 011 to reach them. As such, users will have to be a member of a voice policy that allows international dialing.
2. US/Canada - Treat calls to anywhere in US/Canada as national calls, excluding the Caribbean. To dial Caribbean countries, users will have to be a member of a voice policy that allows international dialing. Not available for Caribbean rulesets.
3. US/Canada/Caribbean - Treats calls to anywhere in NANPA (US/Canada/Caribbean) as national calls (along with the potentially higher call costs).

If you are creating a ruleset for a Caribbean country that uses +1 as the country code, you won't be able to select US/Canada, since this would make dialing within that Caribbean country difficult.

Selecting the Simple Ruleset option prevents usage of this feature, and will default to US/Canada/Caribbean. You won't be able to control how people dial other NANP countries when there is only a single simple routing rule.

So, there you go.  A lesson in the finer details of dialing numbers in North America that the rest of the world might not be aware of. Try to contain your excitement.

Using the Lync Optimizer to Configure a Single Multi-Country SIP Trunk

As SIP trunking becomes more reliable and trusted, companies are taking advantage of the ability to consolidate standard PSTN phone lines from multiple office locations into a single SIP trunk.  Most of the larger SIP providers can provide phone numbers for multiple countries, allowing for even further consolidation of telephony resources.

Skype for Business is very well suited to this sort of consolidation.  Typically, larger companies deploy large centralized Enterprise Edition pools in a few central datacentres that serve offices spread across entire continents.  These centralized pools in turn connect to a SIP trunk over a trusted, secure connection.

As mentioned, these SIP trunks can provide phone numbers for multiple countries, and price those calls as if they originated from those countries.  So, if a company has a SIP trunk in London, UK, they can give out phone numbers to other countries.  For example, users could have Germany-based phone numbers served out of the London SIP trunk, and calls from those numbers would be priced as if they originated from Germany. If a German user placed a call to another German phone number, they would be charged as a local or national call, even though the SIP trunk may physically reside outside of Germany.  Conversely, if that same German user called a London phone number, the call would be charged as an international call.

Setting up Skype for Business dial plans and voice policies in this situation can get tricky, but fortunately I've come up with a very clean and easy to execute plan on how this can be accomplished using the Lync (Skype) Dialing Rule Optimizer.

Let's use an example of a company with a central Skype for Business deployment in London, UK with a single SIP trunk assigned to that location.  This company has offices in the following locations:

• London, UK
• Berlin, Germany
• Paris, France

All user phone numbers for all three locations are hosted out of the London SIP trunk.

The company has the following requirements:

• Users must be able to dial as they are accustomed to in their respective country
• Must be able to limit dialing for certain groups to the local, national or international level for their respective country

Let's assume this is a greenfield deployment, and nothing has been done yet in terms of Enterprise Voice configuration outside of getting the London SIP trunk connected to Skype for Business.

The first thing to do is to generate rulesets for each of the three locations using the Dialing Rule Optimizer.

First, London:

Then Berlin:

Note that I selected the "Force English Rulenames", which I did just because I can't read German or French and would prefer English rule names and descriptions throughout my Skype for Business deployment.

And finally Paris...

The resulting .PS1 rulesets are then copied to one of the Skype for Business servers. 

First, the London ruleset is applied to the deployment, creating user-level dial plans and voice policies when prompted.  When complete, there will be a single London dial plan and 3 voice policies. All routes use the single SIP trunk (as you would expect, since its the only one available).

Dial Plan page after running London ruleset

Voice Policy page after running London ruleset

In this state, we can easily assign a UK dial plan and voice policies to UK users as appropriate.

Next, run the rulesets for Berlin and Paris.  This is done for multiple reasons. Firstly, it will create German and French dial plans, so users in those countries can dial numbers as they do in those countries.  Secondly, it will allow administrators to assign country-specific local, national and international policies.  Someone assigned to a German national policy will only be able to dial phone numbers in Germany and nowhere else, regardless of the physical location of the SIP trunk.

When running the rulesets, make sure NOT to select the option to use least-cost routing. Least-cost routing only works with multiple SIP trunks from different providers. With a single SIP trunk, as in this example, implementing least-cost routing adds unnecessary PSTN usages to voice policies that ultimately don't accomplish anything.  If we make a call from a German number to London using a London route, the call will still be billed as an international call from Germany, as the SIP provider will see the German number as the source and bill accordingly.

To make things easier and faster to run, I recommend the use of the multiple PowerShell command-line switches available with rulesets.  It makes applying multiple rulesets faster and less prone to errors.  For the rulesets in this example, I used the following switches (using the Paris ruleset as an example):

 .\FR-Paris-Lync.ps1 -SiteID 1 -DialPlanType user -LeastCostRouting:$FALSE -OverwriteSiteVoicePolicy:$FALSE -LocationBasedRouting:$FALSE -PSTNGateway gatewayname -MediationPool mediationpoolname

For a full listing of the available command-line options, use the command:

Get-Help .\FR-Paris-Lync.ps1 -Full

Once done, the dial plans and voice policies will look as below.

Dial Plan page after running Berlin and Paris rulesets

Voice Policy page after running Berlin and Paris rulesets

This might seem more complicated than absolutely necessary, and you would be right. You could certainly just use London-based rules for all locations, but it would limit your options severely.

Setting up things in this way will allow users to dial numbers exactly as they do at home, and also allows administrators very granular control over dialing capabilities.  Common area phones in Paris can be limited to local dialing in Paris.  First level helpdesk employees in Germany can be limited to dialing only German numbers.

This shows how easy it is to use the Dialing Rule Optimizer to quickly setup flexible dial plans and voice policies in even the largest voice deployments.  If you have any questions about this method, please leave a comment.

Dealing with Trunk Prefixes in Phone Numbers in Skype for Business

First of all, I spend far too much time thinking about dial rules.

For those who don't know, a trunk prefix is a number (or numbers) that typically has to be dialled prior to dialling a phone number within the subscriber's country, but outside the subscriber's home area code.  The trunk prefix is a way to signal the telephone network that the dialed number is a long-distance or national-level call.

For example, the trunk prefix for UK national calls is 0.  If I were sitting in Liverpool and wanted to dial someone in London, I would have to dial 0, then the area code for London (20), then the subscriber phone number (say 3456 7890).  For example, 02034567890.

Not every country uses a trunk prefix, but those that do generally use 0 as a trunk prefix. The actual national trunk prefix usage breakdown (based on my research) is below:

• 101 countries don't use a trunk prefix at all
• 95 countries use 0
• 26 countries use 1 (these are countries that are part of NANPA, like US/Canada and many Caribbean countries)
• Russia and 5 other former USSR states use 8
• Mexico uses 01
• Hungary uses 06

NANPA countries are unique in that the country code 1 is also used as a sort of trunk prefix for long-distance calls. Italy is another unique case in that they don't have a national trunk prefix, but they DO use 0 as the beginning of the area code, which can confuse people.

Trunk prefixes are NOT used outside of the country. Continuing my earlier example, dialling that same London, UK phone number from the US would start with my international call prefix (011), then the UK country code (44), the London area code (20), and finally the subscriber number (3456 7890), resulting in 011442034567890.  If that US person tried to insert the UK national call prefix in the number (0114402034567890), it would fail to connect because trunk prefixes are not used outside the home country.

Now, the UK user shouldn't be expected to know the international trunk prefix for countries other than his own, so when presenting their number on business cards, web pages or emails, they should use the internationally recognized standard for phone number presentation, which is (DRUMROLL)......E.164!!!!  Regular readers of my blog and anyone who knows Lync/Skype for Business should be intimately familiar with E.164 formatted numbers.  If you need a refresher, look back at a very old (from 2010!), but still useful blog post on the subject.

The UK user should present their number like this:

+44 20 3456 7890

However, in many cases the UK user presents their number with the trunk prefix, like this:

+44 (0) 20 3456 7890

or

+44 (0) 203 456 7890

People within the UK understand what the (0) represents, but people outside the UK would assume the 0 is part of the phone number and try to dial it as shown, resulting in call failure. This particular practice is very common in the UK, France and to a lesser extent, Australia. There are likely others (please let me know). Below are some screenshots from various webpages from GLOBAL companies that exhibit this problem:

Astra Zeneca

BAE Systems

Rolls Royce

Since this blog sadly only reaches a very small percentage of the world's population, there's no way I can expect everyone to get their act together and format their phone numbers properly.  Others have ranted about this exact practice before, and it hasn't seemed to help.

As you may be aware, when you're using Internet Explorer with the Skype for Business/Lync client plug-in, many phone numbers on web pages can be directly dialled by clicking the wee little Skype/Lync icon beside the phone number on the right.  You can see this on the Astra Zeneca and Rolls Royce page samples above. You can click those icons, and it will dial the phone number as its presented on the page.  Clicking the number for Astra Zeneca's media department will give you this:

This is not going to work for anybody, since the trunk prefix 0 will be dialled as part of the number and will fail. You might be thinking that you could write a normalization rule that could deal with this, but Lync/Skype for Business will not normalize a number that has a + in front, because it assumes that any number starting with a + is already normalized.  No matter what you do, a phone number that already has the + can't be modified at the source.

If you're anywhere other than the UK, your international routes probably aren't so strict that it would "know" that putting the UK trunk prefix in the number is wrong, so Lync/SfB will happily send the call on through, only to get dumped by your PSTN carrier as an invalid number.

What you CAN do, is create a trunk translation rule that will catch any instances where a 0 is immediately after the country code and strip it before sending it to the PSTN.  There are only a few countries where 0 is actually a part of the phone number (land line numbers in Italy and mobile numbers in the Republic of the Congo), so the regular expression we create can deal with this.

The below rule should work nicely:

Pattern: ^\+(1|7|2[07]|3[0-46]|39\d|4[013-9]|5[1-8]|6[0-6]|8[1246]|9[0-58]|2[1235689]\d|24[013-9]|242\d|3[578]\d|42|5[09]\d|6[789]\d|8[035789]\d|9[679]\d)(?:0)?(\d{6,14})(;ext=\d+)?$

Translation: +$1$2

The first part of the expression with all the digits is the regex for every possible country code in the world. The (?:0) means that if 0 is present immediately after the country code, it will be dropped. Then we accept anything from 6 to 14 other digits.  We separate out Italy (39\d), Republic of the Congo (242\d) to allow for 0 in the cases where they are allowed in those countries.

If you are located in a country that is guilty of the crime of not using E.164 formatted numbers everywhere (I'm looking at you, United Kingdom), then there is the additional step of modifying the appropriate voice routes to allow for numbers coming through the system with a 0 in the wrong spot.  Using UK's national route as an example:

Old route pattern: ^\+44(1[1-9]\d{7,8}|2[03489]\d{8}|3[0347]\d{8}|5[56]\d{8}|8((4[2-5]|70)\d{7}|45464\d))$
New route pattern: ^\+440?(1[1-9]\d{7,8}|2[03489]\d{8}|3[0347]\d{8}|5[56]\d{8}|8((4[2-5]|70)\d{7}|45464\d))$

Note the presence of the 0? after the +44, which indicates that 0 may or may not be present for the route pattern to match. As of right now, the Optimizer will create modified routes only for countries that I'm aware of that flaunt the E.164 rules on a regular basis:

• UK
• France
• Australia

If there are others, please let me know, either directly or via blog comments.

All the above logic has been incorporated into the Lync/Skype4B Dialing Rule Optimizer, so if you are using that tool for creating your EV dialplans/routing, then you'll be covered.

Testing Inbound PSTN Connectivity Directly from Lync/Skype for Business

File this one under "It's obvious once you think about it for even a second"...

I was recently attempting to get a SIP trunk working to a new Sonus gateway located in Event Zero's head office in Brisbane, Australia.  I wanted to test inbound calls to the gateway by calling one of our response group workflows.

Normally, I would pick up my mobile or home phone and dial the number to test, but since I was dialing Australia, and I'm a cheap bastard, I didn't want to do that.  It was also the middle of the night in Australia, so I couldn't get someone local to do it for me.  If I dialed the number from Skype for Business, then it would do a reverse-number lookup, find an internal match and route me to the response group internally without going through the PSTN, which wouldn't achieve my goal.

My goal was to route a call to our Australian response group via Skype for Business via the PSTN in the easiest, laziest, least-expensive-to-my-own-wallet way possible (this is sounding like an exam question).  Pick one of the following answers:

1. Suck it up princess and eat the $2.05 it will cost to call Australia for a few seconds.
2. Wake up someone in Australia at 2 in the morning, claiming its an emergency.
3. Convince yourself that since outbound calls work fine, inbound should too.
4. Use a trunk translation rule to route a dummy phone number to the correct destination.
5. Give up and start drinking, because its Friday afternoon dammit!

The correct answer is #4 (although the judges will also accept #5).

If you've ever been at one of Doug Lawty's Enterprise Voice sessions at LyncConf or Ignite, you have probably seen his infamous diagram showing how a PSTN call works its way through the system.  To save you the pain, here the relevant details in a very small nutshell:

1. Dialed number gets normalized to E.164
2. Skype for Business does a reverse number lookup to see if there's an internal user or service that is assigned that number. 
3. If there's a match, routes the call internally directly to the user/service.
4. If there isn't an internal match, it finds a valid route through a PSTN trunk
5. It applies any outbound number translation to make the number conform to local standards and sends it on its merry way out the gateway to the PSTN.

Since reverse number lookup happens before handing off the call to the routing engine, we can simply call a dummy PSTN number of our choosing, and once it reaches the trunk translation rule stage, change that dummy number back to the proper number assigned to the Response Group workflow.

In the above example, all I do is create a trunk translation rule to change the non-existent North American phone number +1 (555) 999-0000, and translate it to the proper number.  Once the call has progressed to the point where outbound translation is happening, Skype for Business won't be doing another reverse number lookup, so it will continue to route that number out to the PSTN, at which point it should route to the correct destination (which could be right back where it came from). 

So, a simple solution to overcome my unwillingness to waste money on stuff I don't have to.

Selective Caller ID Blocking in Lync/Skype for Business

Once in a while, a customer asks how they can block caller ID on outgoing calls in Lync/Skype for Business. If they're interested in blocking caller ID on all calls, then the answer has always been simple: use the Alternate Caller ID field in Voice Routes.

Easy enough, right? But what if administrators want to give users the ability to selectively block caller ID at the individual call level?  When on the traditional PSTN, users in most places can enter a code prior to dialing the number if they want to block their caller ID.  In most North American markets, this code is usually *67.  So, a user could dial *6715552224444 and their caller ID would be blocked for that call.

In Lync/Skype for Business, you can replicate this functionality but it takes some work. Since the caller ID blocking feature is done at the route level, you will need to have a separate route for calls with an alternate caller ID.  For calls to use that route, you will need some unique signifier that would not occur in normal day-to-day dialing.

Since the caller ID block code you use on the PSTN should be unique, you can incorporate that into your dialplan, routes and trunk translation rules.  When I first tried this, I wanted to use *67 in my dialplan, but the Lync client didn't like the * so much. It threw up the virtual equivalent of giving me the finger and refused to work, so I had to go about it differently.  Thankfully, things have improved recently so that the Skype for Business client will happily accept the * (or # if you want).

My earlier version of this blog post simply put the *67 in front of the number and sent it through the system, stripping the *67 just before sending off to the PSTN.  Kevin Bingham from Cerium Networks suggested it might work by adding a custom parameter suffix, such as ;callerid=blocked (custom parameters are allowed by RFC3966).

So, after a bit of trial and error, I managed to make it work. This method is much nicer as it conforms to the standard RFCs and is fully E.164 compliant. Also, when someone types *67 and a number, it normalizes without showing the parameter suffix, which looks nicer to the user.

Here's a simplified example using the North American dialplan. First, you'll need a normalization rule in your dial plan that will accept the caller ID block code.

Pattern: ^\*67(\d{10})$
Translation Rule: +1$1;callerid=blocked

This will take any number that starts with *67 and is 10-digits long and translate it to +1 then the 10-digit number, followed by ;callerid=blocked. The client won't see this part of the normalization string.

Then you will need a special route that will accept numbers with that pattern and will apply the alternate caller ID:

Make sure you assign the appropriate PSTN gateway to the route and add the voice route to the appropriate PSTN Usages.

Finally, you will have to create a trunk translation rule on the selected trunk to strip the ;callerid=blocked from the dialed number before sending it out to the PSTN.

I've tested this using the latest Skype for Business server and client (as of August 2015), and the 5.4 firmware on a VVX 600 as well as a CX600 deskphone.  Let me know if this doesn't work on an older platform. I originally attempted this several years ago, and the Lync client (or server...can't recall), didn't deal with the *67 so well.

Incidentally, you might have issues with the alternate caller ID not being sent.  I've seen this on our own SIP provider.  Checking the SIP traces, I can see that I'm presenting the alternate caller ID as a P-Asserted-Identity, which is the way it should work, so my SIP provider seems to be ignoring it.

The example above used "callerid=blocked" as the custom parameter. You can name your custom parameter whatever you want as long as it is in lower case and uses the same format as ;parametername=value. Custom parameters have to also be placed after any ;ext= parameter.

As you might expect, I've incorporated this functionality into the Lync Optimizer.  Try it out and let me know how it works for you.

Lync Enterprise Voice Misconceptions #3 - Inter-trunk Routing

During my travels across the Lync Enterprise Voice landscape, I come across numerous Lync deployments that make some fundamental mistakes in how to manage phone numbers, call routing and other details.  I've covered a lot of these details in parts of my OTHER Enterprise Voice Best Practices, but its obviously a lot to take in, and I've seen enough of the same sort of errors in the wild that prompted me to do this series.

Last week's episode talked about how to properly use the external access prefix in Lync. This week, we're talking about...

#3 - Inter-Trunk Routing

If you've ever manually created trunk translation rules for a PSTN gateway in Lync, you've probably noticed the "Associated PSTN Usages" section.

The wording is vague, and even Technet's description of the setting doesn't tell you much.

From what I've seen in multiple deployments, people tend to add the PSTN Usages that were created specifically for the particular trunk, which sort of makes sense if you use Technet's description as your only guide.

Some other places on the Internet take this idea even further, and imply that this section is used to define the PSTN usages that are allowed to use the specified trunk. If you think about it, you already accomplish this by defining the PSTN Usage/route combination without having to do anything else, so that can't be right either.

Now, you might be aware that Microsoft mentions in their Technet planning documentation that Lync can do "inter-trunk routing".  From their own documentation:

This new capability enables Lync Server to provide call control functionalities to downstream telephony systems. Intertrunk routing can interconnect an IP-PBX to a public switched telephone network (PSTN) gateway so that calls from a private branch exchange (PBX) phone can be routed to the PSTN, and incoming PSTN calls can be routed to a PBX phone. Similarly, Lync Server can interconnect two or more IP-PBX systems so that calls can be placed and received between PBX phones from the different IP-PBX systems.

In more general terms, Lync can pass inbound phone calls on to a different destination, which could be another PBX system or even back out to the PSTN.  So, now you're thinking "That's a great feature, but what does this have to do with Associated PSTN Usages?"  Since the title of this article says "Inter-Trunk Routing", it should dawn on you that "Associated PSTN Usages" has something to do with inter-trunk routing.  If it doesn't, then lie down a while and come back after a good nap.

As you hopefully have surmised by now, inter-trunk routing is done using "Associated PSTN Usages" from within a trunk.  The details behind how to do this are helpfully discussed in some of my own blog posts, Technet and also those by fellow Lync MVP Richard Brynteson:
http://ucken.blogspot.com/2013/06/inter-trunk-routing-in-lync-2013.html
http://masteringlync.com/2013/06/07/inter-trunk-routing-deep-dive/
http://technet.microsoft.com/en-us/library/gg425831.aspx

To summarize those blog posts, if an incoming call from a trunk can't be routed to an internal user, it will attempt to route the call to an alternate trunk, if there is a matching PSTN Usage/route combination assigned to the incoming trunk.

When people add the PSTN usages to a trunk that are already assigned to that very same trunk, incoming calls could potentially be sent back out the same way they came in, if there isn't a matching user in Lync. This could result in odd behaviour, including calls bouncing back and forth between a PBX and Lync, in what I call the "Telecom Routing Donut of Doom".  Fortunately, in most cases, adding PSTN usages to the trunk has no effect, since there is almost always a Lync user assigned to the incoming phone numbers.

I've seen numerous deployments where they've added PSTN usages willy-nilly (my Word-of-the-Day calendar entry for today).  If I see those, my next question is "Oh, so you're using inter-trunk routing."  If the reply I get back is some variation of  "What's inter-trunk routing?", then I remove those PSTN usages from the trunk configuration.

There you have it.  Tune in next time (not necessarily next week, since I'm bad at reading calendars) where we talk about something else that I haven't quite figured out yet.

Lync Enterprise Voice Misconceptions #1 - Failover Routing

During my travels across the Lync Enterprise Voice landscape, I come across numerous Lync deployments that make some fundamental mistakes in how to manage phone numbers, call routing and other details.  They're always fixed by the end of the engagement, but I'd like to share some of these to help keep others from making the same mistakes.  This will be an ongoing series of unknown duration.

#1 - Failover/Resiliency Routing

This is one of the more misunderstood concepts in Lync Enterprise Voice. Its a question that often trips people up on the Lync Voice exam (70-337), and is something that even respected websites like Windows IT Pro gets wrong (despite my attempts to get them to correct it).

The idea behind failover or resiliency routing is that you want to use a particular PSTN gateway for your normal day-to-day call routing, but have a backup PSTN trunk ready in case the primary one is down. This is different from load-balanced routing, where your goal is to evenly spread call traffic between two or more trunks.

For example, say you have a Lync deployment in your Boston office and another one in your Seattle office.  For reasons that should be obvious, you want to ensure that your Boston users always use the Boston PSTN gateway for outbound calls to reduce WAN traffic and call latency. If the Boston trunk is down, calls should failover to the Seattle PSTN trunk.  The same goes for your Seattle users. We could make things more interesting by bringing least-cost routing into play, but we're going to keep it simple here.

A common error people make in an attempt to make things simple and easier to manage is to create a single route for all calls, and place both the Boston and Seattle trunks inside that route.  Since they added the Boston trunk first, it appears first in the list, and they are lulled into thinking that calls will always use the Boston trunk unless its down, at which point the Seattle trunk is used.

In actual fact, calls will load-balance themselves between the Boston and Seattle trunks. Sure, if Boston is down, all calls will route via Seattle, but any well-designed EV deployment should never needlessly send calls across the country on the corporate WAN unless absolutely necessary.  If your other site is in a different country, you could be left with some pretty high phone bills since half of your national calls will be routed out the other country's gateway as an international call.

Voice Policy	PSTN Usage	Route	Trunks
Global	AllCalls	AllCalls	BostonGW SeattleGW

A clue to this behaviour can be found when you look at a route in the Control Panel.  You'll notice that while you can add/remove trunks to a route, there is no way to change the order of the trunks. This should be a clue to the fact that you have no control over which trunk is used within a route.

The proper way to achieve failover routing is via PSTN Usage ordering. Instead of creating a single route with multiple gateways inside it, you create a Boston PSTN Usage with a route to the Boston PSTN gateway, and another Seattle PSTN Usage with a route to the Seattle gateway.  In the voice policy assigned to your Boston users, add both the Boston and Seattle PSTN usages, ensuring the Boston one is above the Seattle one.  For your Seattle voice policy, put Seattle first.

Voice Policy	PSTN Usage	Route	Trunks
Boston	Boston-AllCalls	Boston-AllCalls	BostonGW
	Seattle-AllCalls	Seattle-AllCalls	SeattleGW

Now, you have achieved true failover routing.  For Boston users, all calls will route out the Boston trunk, unless it is down.  The same thing works for your Seattle users.

Incidentally, putting multiple trunks  in a single route does have its uses. If you have multiple PSTN gateways within the same datacentre for redundancy, its OK to do things this way, since you usually don't really care which trunk is used for outbound calls. Calls will be load-balanced between all the trunks, skipping any gateways marked as down. The above picture shows exactly that situation (although its not obvious since most of the trunk name is truncated). However this should never be considered failover routing, simply round-robin or load-balanced routing.

Voice Policy	PSTN Usage	Route	Trunks
Boston	Boston-AllCalls	Boston-AllCalls	BostonGW1 BostonGW2
	Seattle-AllCalls	Seattle-AllCalls	SeattleGW1 SeattleGW2

Essentially, you want to avoid placing trunks from different locations within the same route. This ensures you have control over how your calls are routed, keeping WAN utilization and costs low.

Tune in next week for our next exciting episode: "PBX External Access Prefixes"

Location-Based Routing without Inbound Call Restrictions

The February 2013 Update for Lync Server 2013 (CU1) added location-based routing to the Lync Enterprise Voice featureset. As described on Technet and various other blogs, location-based routing was designed to function in countries where routing calls over the WAN is not allowed.

Countries like India apparently have rather strict telecom laws saying any calls that exit the country must exit via the PSTN.  For instance, imagine your company has a Lync deployment in India and Canada.  As I understand it, if a user sitting in India wanted to call a Canadian PSTN number, it couldn't save on international toll charges by routing the call to Canada via the corporate WAN and exit to the PSTN via the Canadian Lync deployment. The converse situation would also not be allowed.  Whether this is because India wants the international toll charge revenue or for monitoring purposes, I don't know.

Prior to Lync 2013 CU1, companies faced with these requirements would be OK when users never moved from their assigned location.  For instance, if a Canadian user never went to the India office, and the India users always stayed in India, they would never run afoul of the rules. If a Canadian user did travel to India, their Canadian voice policy would still apply (unless the administrator moved the user temporarily to the India Lync server).  Their calls would route over the WAN to the Canadian Lync server, which is not allowed by India telecom rules.

Location-based routing was obviously added to Lync to deal with the "India problem".  You can see this in the Technet documentation on how to setup location-based routing.  All the examples use India, and if you follow the documentation explicitly, you will have an India telecom compliant Lync deployment.  If our hypothetical Canadian user travels to the India office, their calls will use the India Lync deployment, rather than use the WAN for least cost routing.  Inbound calls to the Canadian user's Canadian phone number will go to voicemail, because letting him take the call via the WAN would run afoul of the India dial rules.

So, this got me thinking. What if we want to setup location-based routing, but not worry about whether or not inbound calls can route over the WAN?  I can think of many situations where location-based routing is desirable. Any place where you have lots of mobile people going to different offices can benefit from location-based routing, especially in environments where bandwidth back to the user's home pool is lacking.

Luckily, I'm working on a Lync 2013 deployment that has that exact scenario in mind. The company has many mobile users who travel to far-flung offices with poor WAN conditions.  I wanted to see if we could implement location-based routing for this company, but without the restrictions on inbound call routing imposed if you follow the Technet documentation to the letter.

The documentation has you setting up all your sites and subnets, and then running the following commands (as per http://technet.microsoft.com/en-us/library/jj994036.asp):

1. New-CSVoiceRoutingPolicy to create the routing policies and the PSTN usages assigned to it
2. Set-CSNetworkSite to enable location-based routing for the site via -EnableLocationBasedRouting:$TRUE, and to assign the previously created voice routing policy
3. Set-CSTrunkConfiguration to assign network sites and enable routing restrictions on the PSTN trunk, using -EnableLocationRestriction:$TRUE.
4. Set-CSVoicePolicy to enable location-based routing for the users assigned to that policy, using -PreventPSTNTollBypass:$TRUE

We setup location-based routing as per the documentation with only ONE key difference...we didn't enable location-based routing on the trunks as per the examples given.  When running Set-CSTrunkConfiguration, we left out the -EnableLocationRestriction:$TRUE setting.

Technet's documentation on this particular setting seems to indicate not setting -EnableLocationRestriction to $TRUE would make location-based routing not work. In actual fact, this is the setting that stops inbound PSTN calls from working while a user is at a site where call routing restrictions apply (like India).

The setting that I THOUGHT would have allowed inbound calls across the WAN to work was Set-CSVoicePolicy -PreventPSTNTollBypass:$FALSE.  This setting is actually the one that controls which users will get location-based routing applied to them.  Setting it to false disables location-based routing for the users of that voice policy, as indicated by the wording on the location-based routing setup page. It does not actually prevent PSTN calls from reaching users over the WAN, as the Technet documentation on the command indicates.

We've tested this setup and it works as we had hoped it would. When users go to remote sites, their outbound calls use the local PSTN egress point, but inbound calls to their PSTN phone number still routes to them properly.

So, in conclusion, if you want to enable location-based routing without inbound call restrictions, don't use Set-CSTrunkConfiguration -EnableLocationRestriction:$TRUE, or conversely, use Set-CSTrunkConfiguration -EnableLocationRestriction:$FALSE if you've already set it to $TRUE.

Inter-trunk Routing in Lync 2013

Introduction - What is Inter-trunk Routing?

Inter-trunk routing is a new feature in Lync 2013 that allows Lync Server to be the central call processor for a multi-PBX deployment.  In previous versions, Lync was only capable of being the final destination for phone calls.  If an inbound phone call couldn't be matched to a Lync user, the call would fail.  There was no way to have Lync forward calls on to another PBX, which limited the configuration options available to administrators.

Inter-trunk routing gives Lync administrators the ability to take calls in from a variety of sources and forward them on to other non-Lync destinations if there isn't a matching Lync user with the target phone number. 

The Problem

Recently, I had to deploy inter-trunk routing for a Lync deployment that had calls coming in from a variety of sources to a centralized Lync Server 2013 Enterprise Edition deployment:

• a Lync-certified SIP trunk
• a Canada-based T1 line connected to a PSTN gateway
• two US-based Mitel PBXs. 

The inter-trunk routing requirements were very specific: forward four phone numbers entering Lync from the SIP trunk to one of the US-based PBXs.  The four phone numbers were +1 (289) 555-3926, +1 (289) 555-6733, +1 (289) 555-6734 and +1 (289) 555-6780.

The Solution

Having never done Lync inter-trunk routing, I turned to the trusty Internet for answers.  I found lots of information on WHAT Lync inter-trunk routing was all about, but almost nothing on exactly HOW to configure inter-trunk routing in Lync.  I saw references to assigning PSTN usages to trunks, and saw the place in the Lync Control Panel to add it, but nothing but vague allusions to the process of actually implementing it.

UPDATE 10-June-2013: Richard Brynteson posted a more knowledgable deep-dive into inter-trunk routing mere days after I posted this. I made a slight adjustment to my process based on what I read in his blog, so its definitely worth reading.

As usual, when I come across such a situation, I assume that it must be so simple to configure that it didn't occur to anyone to actually document the HOW.  I then assume I must be a complete idiot for not knowing something so plainly obvious to every other Lync administrator on the planet. So, after much flailing around, I figured out a solution that works using inter-trunk routing.

Since I wanted to route only four specific phone numbers between trunks, I needed to make sure that I enabled inter-trunk routing for those numbers and no others.  If I allowed inter-trunk routing for too wide a range of phone numbers, we could get into a situation where calls could enter Lync, pass onto the target PBX and route back into Lync, causing a call loop.  Rather than leave it to the target PBX to ensure a call loop doesn't happen, I figured it best to ensure Lync only pass the specific numbers to the PBX.

I started by editing the site-level voice policy attached to the Lync site where the incoming SIP trunk calls came into Lync.  I created a dedicated PSTN usage/route combination for those four numbers.  The PSTN usage was called NA-ON-Cooksville-289555-MitelForward to keep with the naming convention used by the Lync Dialing Rule Optimizer.  The route was called NA-ON-Cooksville-289555-MitelForward with a route pattern of ^\+1289555(3926|67(33|34|80))$ pointing to the PBX at 1.1.1.1. 

The PSTN usage was placed at the very top of each voice policy's PSTN usage list to ensure that any Lync user that tries to dial those numbers will forward the calls to the desired PBX. For good measure, I also added the PSTN usage to the Global voice policy, although I'm not sure this is necessary.

Next, I assigned the new PSTN usage to the incoming SIP trunk under Trunk Configuration.  If the trunk doesn't exist, add it as a new pool trunk.  I then added a trunk for the PBX and added trunk translation rules to strip the number down to 5 digits, which is what the target PBX is expecting.

Once done, I committed the changes and waited a few minutes for the changes to bake to a nice golden brown.

The moment of truth came when I was able to call one of those four numbers and listen as Lync seamlessly passed the calls onto the Mitel PBX.  Great success!

Conclusion

I'd like to say it was my deep, Yoda-like knowledge of how call routing works in Lync that allowed me to think through the process of determining how inter-trunk routing works. Unfortunately, the truth is that I tried random combinations of things until I stumbled blindly onto the solution.  There's a reason why I chose that picture of the Hoff looking vacant and stunned at the same time as my avatar....it's how I look and feel much of the time.

To summarize the process:

1. Create a PSTN usage/route combination that is specific to the phone numbers required to be forwarded to the PBX.
2. Place the PSTN usage at the top of all voice policies to ensure that both inbound calls from the PSTN and calls made by internal Lync users are routed to the proper destination.
3. Assign the PSTN usage to the incoming trunk.

When complete, the whole call process should function as follows:

1. Inbound call comes into Lync via SIP trunk.
2. Lync normalizes the number into an E.164 phone number
3. Lync does a reverse number lookup to check for a Lync user with the same number
4. If no match in Lync, then it looks for a matching usage/route assigned to a trunk
5. When found, applies any outbound normalization rules and sends the call to the next hop

For a more detailed description on how the call flow will proceed, check out the Mastering Lync blog.  Richard Brynteson did a series on the nitty gritty details behind dialing behaviours in Lync. His post on Inter-trunk dialing is a deep-dive into the details that I don't get into here.

If there's anyone else out there trying to figure out how to implement Lync inter-trunk routing, I hope this helps figure things out.  As always, if you have any questions or can correct any misunderstanding I might have on the process, just leave a comment.

Least-Cost/Failover Routing in the Lync Dialing Rule Optimizer

The Lync Dialing Rule Optimizer tries to take care of all the Enterprise Voice configuration necessary for all deployments.  On most fronts, it does a pretty good job (IMHO).  One area that has been lacking is the ability to automatically arrange PSTN usages to provide least-cost/failover routing for multi-site Lync deployments. Once an administrator has run the Optimizer for all their sites, they have to manually configure the voice policies to provide least-cost/failover routing.

If you're not familiar with how least-cost/failover routing works in Lync, please refer to my post on the subject in my Lync Enterprise Voice Best Practices series.

With version 9.0 of the Lync Dialing Rule Optimizer, Lync administrators now have the option to create least-cost/failover routing between all sites that have been deployed using the Optimizer (or at least follows the same naming conventions used by the Optimizer).

When the Optimizer-generated script detects multiple Lync sites, it will prompt the user if they want to apply least-cost/failover routing to the voice policy being generated.  If the user allows it, the Optimizer will add PSTN usages for all the other sites to the new voice policies.  This assumes the existing PSTN usages are named with the country abbreviation first, and ends with either Local, National, International etc in any of the languages currently supported by the Optimizer as in the following examples:  UK-Leeds-113-Local, IT-Rome-06-Nazionali.

The output can be best summarized by way of example.  Assume a company has Lync Enterprise Voice deployed in the following locations:

Toronto, Canada

Vancouver, Canada

London, UK

Rome, Italy

Belém, Brazil

After running the Optimizer script against all sites, the PSTN usages for the Toronto International user voice policy would look like this (you might want to sit down for this):

NA-ON-Toronto-416567-Local

NA-BC-Vancouver-604678-Local

NA-ON-Toronto-416567-National

NA-BC-Vancouver-604678-National

NA-ON-Toronto-416567-Premium

NA-BC-Vancouver-604678-Premium

NA-ON-Toronto-416567-Service

UK-London-20-Local

IT-Roma-06-Locali

BR-Belém-91-Local

UK-London-20-Mobile

IT-Roma-06-Cellulari

BR-Belém-91-Celular

UK-London-20-National

IT-Roma-06-Nazionali

BR-Belém-91-Nacional

NA-ON-Toronto-416567-International

NA-BC-Vancouver-604678-International

UK-London-20-International

IT-Roma-06-Internazionali

BR-Belém-91-Internacional

The Optimizer will group PSTN usages from the same country near the top, using the assumption that most of the calls will be made to in-country locations and that the fewer PSTN usages the system needs to evaluate for each call, the better.

The ordering is such that least-cost routing and failover routing will occur.  PSTN usages from other countries will be placed lower in the list while still providing least-cost and failover routing for all calls.  If there are multiple Lync sites out-of-country, the ordering of PSTN usages within the National and International usages will be somewhat random. Administrators should review the PSTN ordering to make sure it suits their needs.

It is assumed that premium numbers can only be dialed from in-country locations, so out-of-country premium PSTN usages are not assigned. Also, only the local service PSTN usage is assigned for similar reasons.

All calls will use the least-cost route where possible. If a route assigned to a specific usage is unavailable, calls will use a route in another site, again keeping the call in-country if possible.

With the inclusion of least-cost/failover routing in the Lync Optimizer, administrators now have a tool that can completely build the Enterprise Voice environment for even the largest enterprise-level Lync deployment.

As always, feedback is greatly appreciated. Let me know if you come across any issues with functionality or scalability as I haven't tested if there is a limit to the number of PSTN usages that can be assigned to a voice policy.

Lync Enterprise Voice Best Practices - Usages and Routes

Over the past while, I've typed some lengthy posts about the importance of E.164 phone number formatting and my take on normalization best practices. Now to pull it all together for the final act, I'll be talking about Lync PSTN usages and routes.

When you look at the Voice Routing section of the Lync Control Panel, you'll see the following "tabs": Dial Plan, Voice Policy, Route, PSTN Usage, Trunk Configuration and Test Voice Routing:

From this section, you can manage most aspects of your Enterprise Voice deployment.


Dial Plans were briefly discussed in my previous post.  A dial plan is a collection of normalization rules that are assigned to sites, pools or users.  Dial plans are designed to allow users to dial phone numbers as they are accustomed to, but still outputs properly formatted E.164 phone numbers, no matter what they type. When you create a dial plan at the site or pool level, all users within that site or pool whose Dial Plan Policy is set to Automatic will be assigned that policy.  There can only be one Dial Plan per site/pool.  If one dial plan is assigned to a site and another one to a pool, the pool-level policy will take precedence.  If you want more granular control, you can create user-level dial plans.  You have to assign users to the user-level Dial Plan policy either through the control panel or via Powershell.

Voice Policies define the capabilities of the users assigned to it. Capabilities can include call transfer and call forward, among others. Capabilities also include the types of calls (local, long distance, international etc) members are allowed to make via PSTN Usages.  Voice policies are assigned to users or sites. Site policies will automatically be named the same as the site, while user policies can be given whatever name suits you.

When you create a voice policy, you have the option to associate PSTN Usages to the policy. If you're just starting out, this list will be blank.

PSTN Usages
PSTN usages are the link between a voice policy and a route. The combination of the three determines the calls a user can make and what route the calls will take.  PSTN usages can contain multiple routes, and can be assigned to multiple voice policies.

You can only create PSTN usages through the Voice Policy interface. When you create PSTN usages within a specific voice policy, it will automatically link to that policy.  You can also create routes from within the PSTN Usage creation dialog box, which makes the whole creation process efficient.

PSTN usage names should relate to calls of the same type: like Local, Long Distance/National, or International. If you've got more than one site where PSTN calls will be made and has a defined PSTN gateway, its best to qualify the usages with site information (you'll see why later). I prefer (and this is the same format used for the Dialing Rule Optimizer):  country-state/prov-city-callclass or country-city-callclass.

Some examples:
NA-ON-Toronto-Local
NA-BC-Vancouver-National
NA-TX-Dallas-International
GB-London-National
IT-Rome-Local
JP-Tokyo-International

I tend to use NA (North America) instead of US and CA, because both countries share the same country code (1). Again, if you have a better scheme, go ahead and use it.  There is no right or wrong way to do this.

Routes
Once the PSTN usages are created, I then create routes. If you've followed best practices and ensured that every phone number that enters the system is formatted for E.164, this is where your diligence pays off. A route defines the actual path a call takes on its way out to the PSTN via a defined PSTN gateway. When a user makes a call, a route is selected based on two things: a matching rule (ie. 11-digit numbers starting with +1) and whether that route is part of a PSTN usage assigned to the user.

Don't make the mistake of assigning multiple gateways from different sites in the hopes of achieving failover routing. Lync doesn't use any sort of ordering when determining which gateway to use within a given route.  Its very likely that calls will route equally between the two, which would make for a nasty surprise when the bills come in. For example, don't put gateways from your Toronto and Rome deployments in the same route.  Some calls will route through Toronto, and others will route through Rome.  To properly achieve failover routing, use PSTN usage ordering, as discussed later.

Create routes according to the calls you want to send out that particular gateway.  You can be as generic or as specific as you want.  For instance, you could create a single route called All Calls, and have a matching pattern of ^\+\d+$ (which means accept any call starting with + and at least one digit.).

I prefer to get more granular, even if I won't be imposing limits on the calls users can make. Increased granularity allows you to impose great control over call paths. For instance, you can easily setup least cost routing and backup routes by using properly formatted routes.

I like to setup at least 5 different routes for each gateway: Local, National (long distance), International, Toll-Free, and Service Codes.  As with usages and normalization rules, I like to follow the same naming convention: country-state/prov-city-routeclass or country-city-routeclass.  I assign the routes to the respective PSTN usage.  National and International routes go into the National and International PSTN usages respectively.  Local, Toll-Free and Service Codes all go into the Local PSTN usage.

Each site should look something like this, using Ottawa as an example:

PSTN Usage	Route	Rule
NA-ON-Ottawa-Local	NA-ON-Ottawa-Local NA-ON-Ottawa-TollFree NA-ON-Ottawa-Service	^\+1613\d{7}$ ^\+1(800|888|877|866|855)\d{7}$ ^\+[2-9]11$
NA-ON-Ottawa-National	NA-ON-Ottawa-National	^\+1[2-9]\d{9}$
NA-ON-Ottawa-International	NA-ON-Ottawa-International	^\+[2-9]\d{6,}$

 
Trunk Translation
With your voice policy/PSTN usages/routes all setup, calls should be routed to the proper gateway for sending out to the PSTN. However, the local PSTN provider likely has their own formatting rules for calls that may not be compatible with E.164.

To accomodate these requirements, you create trunk translation rules to add or remove digits from your E.164 formatted phone numbers before sending the call out to the PSTN.  For instance, a Toronto gateway to the PSTN might need to strip the +1 from local calls, strip the + from long distance calls and add 011 to international calls.  Again, the Dialing Rule Optimizer can help create the local ruleset for your deployment.  An example for Toronto would look something like this:

Trunk Translation Rule Name	Pattern	Translation	Sent to GW Example
NA-ON-Toronto-Local	^\+1((416|647)\d{7})	$1	4165551111
NA-ON-Toronto-National	^\+(1\d{10})$	$1	12125551111
NA-ON-Toronto-International	^\+([2-9]\d{6,})$	011$1	011525551111
NA-ON-Toronto-Service	^\+([2-9]11)$	$1	411

If your calls have to route through a PBX before going to the PSTN, you can add the necessary external access prefix here as well. For example (using 9 as the external access prefix):

Trunk Translation Rule Name	Pattern	Translation	Sent to GW Example
NA-ON-Toronto-Local	^\+1((416|647)\d{7})	9$1	94165551111
NA-ON-Toronto-National	^\+(1\d{10})$	9$1	912125551111
NA-ON-Toronto-International	^\+([2-9]\d{6,})$	9011$1	9011525551111
NA-ON-Toronto-Service	^\+([2-9]11)$	9$1	9411

PSTN Usages Ordering
When you have all your usages and routes defined, it is very important to put your PSTN usages in the correct order in your Voice Policies.  When searching for a route, Lync will start at the top of the PSTN usage list and work its way down until it finds a functional route that matches the dialed number.  If the selected route is not available because the gateway is down or can't accept any more calls, then Lync will keep searching for a matching, working route.  Order your PSTN usages so that calls will use the cheapest toll options and also provide failover capabilities. 

Imagine you have a 3 site deployment, with offices in Vancouver, Toronto and Budapest, Hungary.  You've setup your usages and routes according to my guide.  Your PSTN usage for the Vancouver site Voice Policy would look something like this:

NA-BC-Vancouver-Local

NA-ON-Toronto-Local

NA-BC-Vancouver-National

NA-ON-Toronto-National

HU-Budapest-Local

HU-Budapest-National

NA-BC-Vancouver-International

NA-ON-Toronto-International

HU-Budapest-International

In this manner, calls will use the least-cost route for any given call, and should the preferred route not be available, the call will use the next cheapest available option.  The most used usages are positioned at the top to reduce call connection time.  Because every phone number is normalized to E.164, it can be easily routed to any gateway, which will then add any necessary routing codes (like 011) before sending it out.  This may take a fair bit of work to setup, especially with a large deployment with several sites, but I think the benefits outweigh the time involved in setting it up.

Of course, with the flexibility provided by Lync, this is just one method of setting up your Enterprise Voice deployment.  If you've got other ideas or methods, I'd love to hear them.