Cross Tenant Enterprise Voice Teams Migration


Enterprise Voice Teams Migration for Tenant to Tenant


With Team Enterprise Voice you have three choices of PSTN connectivity.

1.       Direct Routing – your own SBC with a PSTN Provider

2.       Operators Connect – hosted and managed SBC booked via M365

3.       Calling Plan – Microsoft operates your PSTN

Each of those solutions have their own migration procedure. Option 2 and 3 is most intense in planning. They wouldn’t allow you splitting phone number blocks into individual numbers or ranges to be migrated. This implies you have to have a migration of users assigned to a range (block) of numbers. Those might mostly not match the planning you have in-place for M365 Groups related/ Channels and will cause strong interference with the user services and their experiences.

If you currently have a phone service provider or carrier and already have phone numbers for your users or services, you need to create a "port order" to transfer those phone number or blocks to to your new carrier. It can be Microsoft for Calling Plans. When the numbers are ported over, you can assign those phone numbers to your users and services such as audio conferencing (for conference bridges), auto attendants, and call queues.

The time for porting towards Microsoft can take between 1-30 days. This depends on your carrier and location/ country.

Other challenges (I might describe in a dedicated blog) are Call Queues, Auto Attendants and more Teams Phones, Conferencing Systems and Surface Hubs.

Those hardware device have their own management solution and you should try aligning hardware based changes with your user migration schedule.

Calling Plan – Microsoft operates your PSTN

With Microsoft Calling Plans, Microsoft is your telephony carrier and operates the telephony for your company/ tenant. Microsoft do not operate in all countries worldwide.

We are talking here about a Tenant to Tenant migration, our focus lies on “porting” between tenant, within the same operator, Microsoft.

Porting within Microsoft takes usually 1-7 hours. This also depends on a phone number ownership. In T2T, it could be a merger with different company names. Make sure you involved Microsoft Porting Team early and making your process transparent.

Another planning effort is based on the local country legal requirements. In certain countries, especially if there is a ownership change involved during the T2T migration, You might be forced to migrate an entire number block. Here to, please consult Microsoft Porting Team before you plan or start your migration.

The LOAs (Letters of Authorization) can be found here:

Manage phone numbers for Calling Plan - Microsoft Teams


But now to the process, how you manage a T2T porting:

Porting can be found within the Teams Admin Center and navigate to Voice/Phone number:

Click the PORT request option.

You also can navigate directly to the wizard:
Phone number porting wizard - Microsoft Teams admin center

For here follow the instruction provided:

Next Steps:

-          Select your country (toll-free or geographical number)

-          Add you phone number (manually or CSV based)

-          Manage number (best use Excel)

-          Add your account information

-          Add your number features

-          Complete your order


I recommend you are using an Excel sheet, so you are able to incorporate the porting date, based on your T2T user migration schedule.

Country or region

Country or regional code

National number

E.164 number
(Country code + National number)






16. Sep. 2022





16. Sep. 2022





02. Nov. 2022

List every phone number, even if they are in a number block.


If you are facing issue during porting:

If you notice any issue with the ported numbers within the first 24-48 hours after the port completed, contact the TNS Service Desk. For any issue that goes beyond 48 hours, contact the Microsoft Support Team.


Popular posts from this blog

How to hide users from GAL if they are AD Connect synchronized

Cannot join external Lync Meeting: Lync Edge Server Single IP Address (Lync Edge Server Single IP Web Conferenceing Problem)

MFA with Guest Access and different tenants settings