Office365 Skype for Business Tenant Dial Plans

Just recently Microsoft made generally available Skype for Business Online Tenant Dial Plans for organizations on Office365. This new capability, which has been in preview for several months, has been a top feature request among organizations who have moved their PSTN calling capability to CloudPBX in Skype for Business Online. In my previous articles I wrote about Deploying Polycom phones for Cloud PBX with on-premise PSTN Connectivity  as well as Cloud Connector Edition (CCE) 1.4.1 Deployment Walkthru Part 1 which are related topics. In this post, I will walk through creating Tenant Dial Pans in CloudPBX and how to use them with Polycom VVX family of qualified IP phones using our test lab environment with an Office365 E5 subscription,

What are Tenant Dial Plans and why do I need one?
Just to recap, dial plan is essentially a collection of digit manipulation (aka normalization) rules that translate dialled numbers into an alternate format (typically E.164) for purposes of call authorization and call routing. Each normalization rule defines a specific number matching pattern and translates the dialled digits based on a regular expression rule. Different dial plans can be assigned different users so that calls can be authorized and routed correctly. In Skype for Business on-premise, a dial plan is used in conjunction with Voice Routes and PSTN Usages in order to determine what calls a user is allowed to make and how to route that call out to the PSTN. Voice routes associate a set of dialled digit matching patterns to set of PSTN Usages and PSTN Trunks. PSTN Trunks define a specific PSTN gateway with a Mediation Server pool. However, prior to the general availability of Tenant Dial Plans  in Skype for Business Online, CloudPBX users were limited to the default country dial plan that was assigned automatically based on the users' location. This default country dial plan was fixed and any necessary number manipulation had to be performed by the PSTN Gateway or IP-PBX that is connected to a CloudConnector (CCE) instance or by an on-premise Skype for Business pool in a hybrid configuration. Below is an example of the default country dial plan for a CCE users based on a Singapore SG tenant:

With the introduction of Skype for Business Online Tenant Dial Plans, users can now be assigned two types of dial plans – service scoped and tenant scoped. The service scoped dial plan is essentially the same as the default country plan mentioned above and cannot be changed. However we can now create tenant scoped dial plans which augment the service country dial plan. Users can now be provisioned with an “effective dial plan” which is a combination of the service country dial plan and the appropriately scoped tenant dial plan. Therefore, it's not necessary to define normalization rules in tenant dial plans that already exist in the service country dial plan.

Tenant dial plans can be further broken into two scopes - tenant scope or user scope. If a tenant defines and assigns a user scoped dial plan, then that user will be provisioned with an effective dial plan of the user’s service country dial plan and the assigned user dial plan. If a tenant defines a tenant scoped dial plan, then that user will be provisioned with an effective dial plan of the user’s service country dial plan and the tenant dial plan. If both a tenant scoped dial plan and user scoped dial plan is defined, the user scoped dial plan takes precedence. To understand more about tenant dial plans and scopes, refer to https://support.office.com/en-us/article/What-are-PSTN-Calling-dial-plans-2f0cfb59-1ca1-4e31-84ce-09d0b1a7ce1b?ui=en-US&rs=en-US&ad=US

Existing Lab Environment
Before proceeding to create and assign tenant dial plans in our tenant, its worthwhile to look at the existing lab environment and how the Polycom VVX phones configured. Our lab environment is a hybrid setup with on-premise PSTN connectivity via a existing Skype for Business FE Pool configured with split-domain with a Office365 E5 tenant. The walkthrough for setting up this environment was already covered in the previous blog post http://www.ucprimer.com/tech-blog/deploying-polycom-phones-for-cloud-pbx-with-on-premise-pstn-connectivity-part-1. The Polycom VVX phone is already signed into an account homed with Skype for Business Online. With regards to dial plans, this environment is configured to use on-premise dial plan by way of setting the parameter using the cmdlet set-cstenanthybridconfiguration -UseOnPremDialPlan $true as shown below

This allows the VVX phone to receive the dial plan and associated normalization rules defined on the on-premise Skype for Business FE Pool. Currently there are just 2 rules :

• Match any 4 digit number starting with 3 and add prefix +656445:  ^(3\d{3})$ ---> +656445$1
  
• Match any 4 digit number and add prefix +656389:  ^(\d{4})$ ----> +656389$1

which are shown in the diagram below:

This allows the phone to receive the dialplan during login as can be seen in the phone log:

For this to work properly we set the phone to use local digit map via the parameter:

• reg.1.applyServerDigitMapLocally = 1

The normalization rules will be applied locally on the phone as digitmaps which can be seen in the phone status menu:

Create Tenant Dial Plan with Normalization Rules
So now we can proceed to create the Tenant Dial Plan using remote Powershell into our tenant. First we create a new tenant dial plan:

• New-CsTenantDialPlan -Identity UCPTenantDP

Next we create a new 7-digit normalization rule and add it to the newly created dial plan:

• $nr7 = New-CsVoiceNormalizationRule -Parent Global -name SG7Digit -Description "SG 7digit TenantDP" -Pattern '^(\d{7})$' -Translation '+656$1' -IsInternalExtension $false -InMemory
  
• Set-CsTenantDialPlan -Identity UCPTenantDP -NormalizationRules @{Add=$nr7}

We confirm the normalization rule is added to the dial plan by retrieving the dial plan again:

• get-CsTenantDialPlan -identity UCPTenantDP

We then assign the Dial Plan to the account that our VVX phone is using:

• Grant-CsTenantDialPlan -Identity vvx@ucprimer.com -PolicyNAme UCPTenantDP

Finally we get the effective dial plan for the account which is basically the new tenant dial plan plus the country service dial plan:

• Get-CsEffectiveTenantDialPlan -Identity vvx@ucprimer.com

All these cmdlets are shown below:

We also change the tenant hybrid configuration to not use the on-premise dial plan by running the cmdlet:

• set-CsTenantHybridConfiguration -UseOnPremDialPlan $false
  

Now that the tenant dial plan has been created, we restart the VVX phones so that in-band provisioning can occur and the phone will get the latest normalization rules from the server. This can be seen in the phone status screen on the web browser admin interface as shown below with the 7Digit normalization rule that we created along with the rules from the default service country dial plan:

Dialling a 7 digit number on the phone now results in a final dial string with '+656' pre-pended.