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Level 2 Contributor

Phone system migration

We are planing to migrate our phone system to Ms teams. 

I am planning to try with addon subscription for phone calling along with domestic calling plan. Some article shows business premiun subscription is eligible for add-on phone system and some article only shows E series subscription are only eligible and E5 already has it included.

Secondly, I am planning to find more articles on someone who has gone through the migration, I wanted to test with initial trial 5 numbers from MS and test autoattended number, call routing and moving the media file for greeting. Once the test phase works then switch the primary test number with production number by porting all primary and all numbers from service provider to Office365, therefore, making the switching process pain-free and interruption free or minimize downtime for phone system during the process.

I may also add trial for few executive users on E5 but it is the switch over process, call queue migration and one autoattended number migration I am worried about

If anyone has moved or migrated their PRI number from vendor and internal phone server to office365, please feel free to share the planning strategy and the implementation process and phases 

Level 1 Contributor


I have been through a number of ISDN/PRI migrations to/from calling plans. MS Teams has a bit more flexibility, and depending on the number os end users, you might want to consider DirectConnect. Feel free to reach out to me directly, matthew.groom@technetuc.com  if you would like to discuss futher. I'd love to help out.



Agreed - we went through the process of moving from Skype On-Prem->Skype Online->Microsoft Teams and had no issues.  There are tons of great planning docs at docs.microsoft.com to help you with the process!  If you are moving from an on-premises make sure you take the time to map out your requirements - because everything you need may/may not be in Teams just yet.

Here is a great place to start: https://docs.microsoft.com/en-us/MicrosoftTeams/tutorial-calling-in-teams



The de-facto reference for the available Add_on licenses is here: https://docs.microsoft.com/en-us/skypeforbusiness/skype-for-business-and-microsoft-teams-add-on-licensing/skype-for-business-and-microsoft-teams-add-on-licensing 

In short - Business Premium only works with Audio Conferencing Add-On, phone system Add-on is not possible, for this you need to upgrade to E3.


For the phone numbers - in this article you'll find the guidance for both scenarios - getting new numbers and porting numbers: https://docs.microsoft.com/en-us/skypeforbusiness/what-is-phone-system-in-office-365/getting-service-phone-numbers At least for my region (Germany) porting numbers works quite smooth according to Partners I'm working with. But maybe others can comment also on important plannind details.

Kind regards, Janosch (Note: Leaving role as of March 2023, don't expect further answers. Connect with me via LinkedIn: https://linkedin.com/in/janoschulmer)