SfB Online: Number porting in the UK


Step by step process

  1. Download and complete the Letter of Authorization (LoA) from the Microsoft site (see link above).
    Note: The “To” Carrier refers to your existing service provider or carrier.
  2. Submit porting form to ptneu@microsoft.com.
  3. You’ll receive a reply back in a few hours with your Port Order ID along with any questions.
  4. Porting is accepted by Microsoft and submitted to the Losing Carrier.
  5. Losing Carrier has 3 days to reject the request or issue a Firm Order Commitment (FOC) notice.
    If accepted, the porting date is confirmed.
    If rejected, engage in back and forth with Microsoft and Losing Carrier to get the information on the form correct.
  6. One day after the FOC notice is received, the numbers will be available in the SfB Online Portal. They will have a status of “Transfer pending”. They can be allocated to users but inbound calling won’t work until the porting is complete. SfBPortal-Pendingtransfer
  7. Three days before the port is scheduled is the last chance to cancel the port.
  8. On the porting day, at some point after the porting time, calls will start being directed to SfB users.
  9. Once the port is confirmed, Microsoft will convert any user numbers to Service numbers.
  10. Crack open a <beverage> and celebrate a job well done.

User experience during the porting window

During the porting window, there should be no disruption to calls.

Outbound calling from SfB will continue to work. Once the port is complete, CLI should automatically update to the new DDI number.

For inbound calling, at some point during the porting window calls will stop ringing on the old handset and start ringing on the SfB client.

Calls that are already established will continue until one party hangs up.

Porting timeline

Based on my experience, the timeline for porting to Microsoft is very similar to other telecoms companies. And will look like the diagram below:


The process is also governed and regulated by OFCOM in the UK, so telcos are legally required to comply with valid requests.

Gotchas and lessoned learnt

  • The form doesn’t ask for it but you will need to provide either the Organisation ID or *.onmicrosoft.com domain.
  • The initial response from the porting team was good, we had the Port Order ID within 30 minutes of emailing in.
  • All numbers are ported in as user number and you can then convert select numbers to service numbers.
  • Pick a migration date at least 20 working days in the future.
  • 3 days notice to cancel a request.
  • Numbers are available in the SfB Online portal once the losing carrier has accepted the request. They have a status of “Transfer Approved”. You can assign them to users at this point, however, inbound calling won’t work till the agreed port day.
  • Converting from a User number to a Service number takes 20 minutes, can only be done once the port is complete and does involve the number being out of service while being converted.

Finding your onmicrosoft.com domain

Admin Console

The organization ID can be found from the Azure Active Directory Admin Center -> Azure Active Directory -> Custom domain names.

From the list search of the <>.onmicrosoft.com entry.



Once you are connected to Azure ID run Get-MsolDomain and look for the <domain>.onmicrosoft.com entry


Finding your Organisation ID

Third Party Website

Some kind folks have built a website that will find your Org ID for you: Link Simply enter your office 365 domain and it will display the Org ID. The site uses OpenID Connect which is an identity layer that sits on top of OAuth 2.0.

Admin console

The organization ID can be found from the Azure Active Directory Admin Center -> Azure Active Directory -> Properties  -> Directory ID.

It looks like a GUID type string. EG. a3gbd34b-14bd-5304-c380-774f60aa533b


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