Port your landline number to VoIP

Can you port a landline number to VoIP?

In most cases, yes. Ofcom sets number portability rules for UK providers in its General Conditions, and Openreach's own advice to businesses moving to digital lines is that "you can usually keep your existing business phone number". UK geographic numbers (01 and 02), UK-wide 03 numbers and Freephone 0800 and 0808 numbers can normally all move to a VoIP phone system.

Once ported, the number is no longer tied to a copper line in one building. It lives on your phone system, so it can ring a desk phone, an app on a laptop and a mobile, follow your opening hours and drop into a menu or queue. VoIP numbers for business explains what changes and what stays the same.

This page covers moving landline and ISDN numbers onto VoIP. For number porting on every route, including mobiles and Microsoft Teams, our sister site has a full guide to business number porting.

Who does what in a landline-to-VoIP port

A port runs the same way round each time. You sign up with the new provider, and the new provider does the asking.

You do not need to contact your current provider to start a port, and you should keep the old service running. Microsoft's published porting guidance for Teams, a useful reference whichever platform you choose, says inactive numbers cannot be ported, so cancelling a line first can lose the number.

The letter of authority and matching details

The letter of authority (LOA) is the signed form that lets the gaining provider request your numbers. The losing provider compares it with its own records, and the same Microsoft guidance names mismatched information as the most common cause of errors and delays to a port. Take these details from a recent bill:

• Account number with your current provider
• Main billing number (sometimes called the billing telephone number) for the account
• Registered business name, exactly as it appears on the account
• Installation address, which can differ from your billing address
• Every number you want to keep, including extra numbers, DDI ranges and any fax or Freephone numbers

If your lines are billed through a reseller, the letter of authority names that reseller and uses the details from the reseller's bill. Avoid moves, upgrades or cancellations on the old account while the port is in progress: open service orders, pending disconnections and account freezes are among the things Microsoft lists to clear first.

Single lines, multi-line installations and DDI ranges

How your numbers are set up today decides what goes on the port request.

Decide whether this is a full port, which moves every number and usually closes the account, or a partial port, which leaves some numbers behind. Some platforms take full ports only: Microsoft's UK guidance says partial ports into Teams Calling Plans are not supported. We can check this before the order is placed. If you are moving a whole ISDN system, ISDN to VoIP covers the routes.

Broadband and other services on the line

A landline often carries more than calls. When a number is ported away, services tied to it can end: Microsoft warns that broadband or ISDN on a ported number is disconnected once the port completes, and the same applies whichever platform you choose.

Before booking the port, check:

• Whether your broadband runs over the line you are porting; if it does, arrange the new connection first. Our sister site covers broadband for VoIP.
• Whether an alarm, lift phone, door entry or card terminal uses the line, and how it will connect afterwards
• Whether the line carries a fax machine you still use, and what replaces it

We can check what depends on each number when we plan the port.

Several accounts, sites or providers

Larger moves often involve numbers spread across more than one account, site or provider: a main number with one company, a fax line with another, and an 0800 number on a third bill. Each account needs its own letter of authority and port request, matched to that account's own details.

Requests for the same account are best sent one after another. If several requests for one account number arrive at the same time, the losing provider can reject one or all of them (another point from Microsoft's guidance), so a later batch waits until the earlier one completes. A phased plan keeps things orderly:

• Group the numbers by account, using each account's own bill
• Port the main numbers and the lines they hunt across together, so a main number is not separated from its lines
• Move one site or account at a time where there are several, so each port can be tested before the next
• Use diverts from the old lines to the new system while you wait, where your current provider offers them

If you are moving a multi-line or ISDN system, the multi-line VoIP phone system guide explains how many calls the new system needs to carry, so capacity is ready before the numbers arrive.

Agreeing the porting date and port day

How long a port takes depends on the losing provider, the number types and how many numbers and accounts are involved, so we confirm the porting date once the losing provider has accepted the request. In the meantime, the new phone system is built and tested so it is ready before the numbers arrive:

1. Users, call flows, menus and voicemail are set up on the new system, often with temporary numbers so staff can test calls
2. Handsets and apps are provisioned and tested on the new system
3. The porting date is agreed with you, avoiding your busiest days
4. On the day, each ported number is rung from outside, and menus, groups and outbound caller ID are checked
5. Any old lines left over are ceased once every number is confirmed working on the new system

Where the numbers end up depends on the platform: with 3CX they port to the SIP trunk provider that serves your system; with Teams they go to Microsoft through Calling Plans, to an operator through Operator Connect, or to a Direct Routing provider such as Forever Teams; with Webex Calling they go to the PSTN option chosen for that location; and with Forever UC they are ported onto the Forever UC service. The platform guides for 3CX VoIP, Teams VoIP and Webex VoIP explain each one.

Contact us with a recent bill and the numbers you want to keep, and we will check them before you commit.