UK Number Porting Process

Number porting is the process of keeping your telephone number when you change supplier.

Technology has made the technical aspect of this process easier for providers to achieve, but the paperwork process involved can be incredibly frustrating. Aside from the commercial and technical relationships required to be in-place between providers before porting is possible, the process of requesting a port has several steps in the process. Understanding this and the lead times involved can be beneficial in your business planning.

Here’s an overview of how the paperwork process works:

  1. A Letter of Authority is required from the end user of a number, stating they delegate authority to port the number to their new provider.
  2. This must be held on file by the Gaining communications provider (GCP) and is transcribed into a standard formatted form, which must then be sent to the Losing Communications provider (LCP).
  3. In addition to the CPs, if you have ported your number previously, the port will also need to involve the Rangeholder (RH) – this is the company who were originally assigned your number in a block of 10,000 numbers, allocated by Ofcom. They will always remain the initial point of contact for incoming calls, in a porting process known as Onward Routing. This may require another post of it’s own. Suffice to say, the GCP must have a relationship with both the LCP and the RH in order to port your number. Porting a previously ported number is known as a subsequent port.
  4. The form is submitted to the LCP, including a requested date and time for it to be actioned, which have industry agreed lead-times depending on the complexity of the request.
  5. The LCP has 48 hours to respond to the request, and either accept or reject it.
  6. If they accept:
    1. If they are not the RH, they will advise this and a request must then be made to the RH
    2. On the agreed date, the LCP will remove the number from their database, and the RH will update their database to forward incoming calls to the GCP
    3. The GCP is then responsible for delivering calls to the customer, or via a reseller, typically via a VoIP platform.
  7.  If they reject:
    1. The rejection will include a reason. Non-payment is not a valid reason, but incorrect or incomplete is the most common reason. This means that something on the form doesn’t match the details the LCP has on file for this number, typically either associated numbers (DDI numbers), or an incorrect postcode.

      Unfortunately, what the LCP has on file and the truth don’t always match up. There is a process to deal with this, known as a Pre-Order Validation (PoV) request.

      A PoV is very similar to the LoA but has some more specific requirements.

      If a PoV request is submitted, the LCP has 5 days to respond with all the details relating to a specific number. This tells the GCP what they need to put on the porting request for the LCP to accept it.

    2. Ultimately the rejection will lead to a re-submit and go back to step 4. The lead-time clock then resets back to the start.

It is common for complex numbering that a PoV is sent prior to the initial request. PoV is not a requirement, and it is possible to resubmit with amended details without a PoV. This may take less time than going through a PoV, but if the amended details are again rejected you can be just stuck in guessing game.


A port request needs to have accurate details about:

  • The installation address of the number
  • The line type, which can be ‘Single’ aka analogue, or ‘Multiline’ aka Featureline, Multiline or ISDN.
  • All associated numbers, which means DDI

One of the difficulties can be that Multiline and Featureline CAN be provided with just 1 line, but they are still considered multi-line.


Industry agreed lead times for porting are as follows:

Regular Port:

Single Line = 4 Working Days

Single Line with more than 10 lines porting at once = 14 working days

Multi Line, fewer than 30 lines with no DDI ranges = 7 working days

Multi Line, 31-150 lines including DDI ranges = 10 working days

Multi-Line, 151 or more lines = 17 working days

Complex DDI ranges / requests = 22 days


Subsequent port (when you’ve ported before):

Single Line = 7 Working Days

Single Line with more than 10 lines porting at once = 17 working days

Multi Line, fewer than 30 lines with no DDI ranges = 10 working days

Multi Line, 31 or more lines including DDI ranges = 13 working days

Complex DDI = 25 days