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Number porting lets you permanently transfer your existing UK phone number from your current provider to Kallin, so that Kallin becomes the host carrier for that number. Unlike call forwarding — where your number stays registered with your old provider and calls are rerouted — a ported number belongs entirely to Kallin. This means simpler billing, lower call costs, and no dependency on your old provider’s infrastructure or configuration.

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What is Number Porting?

Number porting is the legal transfer of a telephone number from one Ofcom-regulated carrier to another. In the UK, Ofcom mandates that all licensed communications providers must release numbers when a customer requests a port, provided the correct authorisation is given. The process is handled electronically between carriers, and in most cases it completes with only a brief interruption to service — typically just a few minutes. Once porting is complete, all calls to your number are delivered directly to Kallin, and your old provider has no further involvement. You can then apply Kallin’s full suite of routing, voicemail, IVR, and analytics features to the number.

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Porting Timelines

The time it takes to port your number depends on the number type. These are the standard working-day timelines in the UK: These timelines begin from the date your port request is submitted and accepted by your current provider. Complex cases — such as numbers on multi-line contracts or numbers associated with legacy ISDN services — may take longer.

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Before You Port

Make sure all of the following are in place before submitting a port request. Incomplete or incorrect information is the most common cause of rejected ports.
  • Confirm you are the account holder at your current provider — only the named account holder or an authorised representative can authorise a port. If you manage the number on behalf of a business, ensure you have the authority to act.
  • Check your number is not under a minimum term contract — some providers will reject a port if the number is subject to a contract that has not yet expired. Contact your provider to confirm, or check your contract end date.
  • Gather your current provider account number — this is printed on your bill or available in your online account. It is required as part of the port authorisation.
  • Obtain your authorisation code — for mobile numbers, this is a PAC (Port Authorisation Code), which you can request from your current network by calling them, texting “PAC” to 65075, or requesting it online. For broadband-linked numbers, you may need a MAC (Migration Authorisation Code).
  • Do not cancel your current service before porting completes — cancelling your line or SIM before the port is finished will release your number back to the number pool, making it impossible to recover.

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How to Submit a Port Request

1

Go to Numbers > Port a Number in your Kallin dashboard

Log in to Kallin, navigate to Numbers in the left-hand menu, and click Port a Number.
2

Enter the number you want to port

Type the number in full, in E.164 format — for example, +441234567890 for a geographic number or +447700900123 for a mobile number.
3

Select your current provider from the dropdown

Choose your existing carrier from the list. If your provider is not listed, select Other UK Provider — Kallin supports all Ofcom-regulated carriers.
4

Enter your account details and authorisation code

Provide your current provider account number and, where applicable, your PAC or MAC code. Double-check these carefully — a single character error will cause the request to be rejected.
5

Choose your preferred porting date

Select your porting date from the calendar. Kallin shows the next available working day and all dates within the standard porting window. Ports cannot be scheduled on weekends or UK public holidays.
6

Review and confirm your request

Review all the details on the confirmation screen. Once you submit, Kallin handles all communication with your current provider, including sending the port request and chasing any responses. You will receive email updates at each stage of the process.

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During Porting

On your chosen porting date, there will be a brief period — usually a matter of minutes — during which your number is being transferred between carriers. During this window, incoming calls may not connect. Kallin will notify you by email when the port is initiated and again when it completes, so you know exactly when your number is live on Kallin. Once the port is confirmed complete, your number is fully active in Kallin and all your routing rules, voicemail settings, and IVR configurations will apply immediately.
Do not cancel your service with your old provider until Kallin has sent you a confirmation that the port is complete. Cancelling early can terminate your number before it has transferred, and it may not be possible to recover it. If you are unsure of the status of your port, check the Numbers > Port a Number section of your Kallin dashboard for a live status update.
Port requests can be rejected for a number of reasons. The most common causes are: account details that do not match your provider’s records, an invalid or expired PAC/MAC code, or a number that is currently under a minimum-term contract. If your port is rejected, Kallin will tell you the reason and guide you through resubmitting with the correct information. See the Porting FAQs for a full list of rejection reasons and how to resolve them.

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Next Steps

Porting FAQs

Find answers to common questions about rejected ports, timelines, and what to do if something goes wrong.

Configure Call Routing

Set up routing rules, schedules, and call queues for your newly ported number.