How to Port a Number into Microsoft Teams Calling
To port an existing number into Microsoft Teams Calling, you'll need account details from your current provider and, in most cases, a signed Letter of Authorisation, before submitting the port request through the Teams admin centre or your connectivity provider. Exactly how you do this depends on which PSTN connectivity method your organisation uses — Calling Plans, Operator Connect, or Direct Routing — since porting is handled differently for each.
Before You Start
Gather this information before submitting a port request, as missing details are the most common cause of a rejected port:
- Your current provider's name and account number
- The full number(s) you want to port, exactly as they appear on your current bill
- A recent bill or invoice from your current provider, usually needed as proof
- A signed Letter of Authorisation (LOA), giving permission for the number to move
- The name and address on the account, which must match your current provider's records exactly
Don't cancel your existing phone service before the port completes. Doing so early is one of the most common ways a port gets rejected or delayed, since a cancelled account can lose the number before the transfer finishes.
How to Port a Number for a Calling Plan
- Go to the Teams admin centre, then Voice > Phone numbers.
- Select Port, then New port order.
- Enter the number(s) you want to port and your current provider's details.
- Upload your signed Letter of Authorisation and supporting documentation.
- Submit the request and choose a requested port date.
- Track progress from the same Phone numbers section — Microsoft will update the status as the port moves through validation, scheduling, and completion.
How Porting Works with Operator Connect
Porting isn't handled through the Teams admin centre when you're using Operator Connect. Instead, your approved telecoms partner manages the port on your behalf, using their own porting process. You'll still need the same information — account details, LOA, proof of ownership — but you'll submit it to your provider rather than Microsoft directly.
How Porting Works with Direct Routing
With Direct Routing, the number itself sits with your SIP trunk provider, not Microsoft. Porting is arranged entirely through that provider's own process, and once it's complete, the number is made available to Teams through your session border controller configuration rather than a Microsoft porting request. If you're moving to Direct Routing from an existing telecoms contract, this is often the most straightforward porting route, since you may already have a relationship with the provider handling it.
How Long Does Porting Take?
Most UK number ports take around one to two weeks from submission to completion, though this varies depending on your current provider, whether all documentation is correct the first time, and which connectivity method you're using. Ports involving multiple numbers or non-geographic ranges sometimes take longer.
Common Porting Problems
Name or address mismatch The details on your port request need to match your current provider's account records exactly. Even small differences, like a missing suite number, can cause a rejection.
Missing or incorrect Letter of Authorisation This needs to be signed by someone with authority on the account, dated recently, and match the format your provider expects.
Losing service mid-port Cancelling your old line before the port completes can result in losing the number altogether. Always let the port finish before ending your existing contract.
Porting rejected with no clear reason This is usually down to a documentation mismatch rather than anything technical. It's worth checking every detail against your current bill line by line before resubmitting.
Frequently Asked Questions
Can I port more than one number at a time? Yes, most porting processes allow multiple numbers in a single request, though very large number ranges are sometimes split for processing.
Will I lose service while the number ports? There shouldn't be any downtime if the port is managed correctly and your existing line stays active until the port completes.
Can I port a number out of Teams Calling later if I switch providers? Yes. Numbers ported into Teams can generally be ported out again to a different provider, following the same type of process in reverse.
What happens if my porting request is rejected? You'll usually be told the reason, most often a documentation mismatch. Correct the details and resubmit — it's rarely a sign of a deeper problem.
Porting delays are almost always down to paperwork, not technical issues — getting it right first time saves weeks. Request a quote if you'd like T2K to manage your port for you, or read our guide to Teams Calling costs if you're still weighing up your connectivity options.
