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Tom Arbuthnot MCSM Communications

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From Which Carriers Can I Port PSTN Numbers into Microsoft PSTN Calling?

Published 10/10/2016 - 0 Comments

Microsoft offer full PSTN carrier services (providing phone numbers and PSTN phone services for users) for Skype for Business Online users in certain countries (US, UK and Puerto Rico at time of writing this blog, and Spain and France in Preview). You can bring your PSTN phone numbers from your existing carrier to the Microsoft service. This process is calling “porting”.


From the Microsoft description:


In general, you can transfer any phone number that is from a supported provider, including:

  • Land line phone numbers.
  • Mobile device phone numbers such as those used for cell phone and tablets, etc. (note there may be some country specific limitations to this, some countries do not allow mobile numbers on a “land line” service)
  • Toll phone numbers.
  • Toll-free phone numbers (note you can port these in, but
  • Service phone numbers such as those used for conference bridges, auto attendants, etc.
  • Fax phone numbers, but they can’t be used for faxing. They will have to be assigned to a user.
  • VoIP phone numbers from a phone provider such as Vonage or RingCentral.


At this time, you can’t transfer any phone number or numbers that aren’t from a supported country. including phone numbers from a VoIP phone provider.

  • Phone numbers used for data connections like for DSL lines or broadband Internet connections.
  • Phone numbers dedicated to faxing.


How Porting works:

Transfer phone numbers to Skype for Business Online


Porting from all carriers is not supported, there is a defined list from Microsoft for each country here:

What phone service providers or carriers are supported?

If your carrier is not on the list, I suggest you raise an advisory support case with Microsoft to see if they can help. The list is being updated on a regular basis.

Update: Microsoft has pulled the list/link. I didn’t get a clear answer as to why other than they don’t want to maintain a list and you should be able to port from anyone. So if you want to confirm if they can port from your carrier you will need to either raise a port request or ask Office 365 support (or your Microsoft account team).

Tom Arbuthnot

Tom Arbuthnot

Principal Solutions Architect at Modality Systems
Tom Arbuthnot is Principal Solutions Architect at Unified Communications specialist Modality Systems. He is a Microsoft Certified Master and MVP, blogger, has a regular podcast with UCToday at and is a regular speaker at events including Microsoft TechEd and Ignite. He co-runs The Microsoft UC User Group London.

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