What is number porting? (and why do you need to know about it...)

⚡ Quick answer: what is number porting?

Number porting lets UK businesses keep their existing phone number when switching to a new provider. Regulated by Ofcom, it applies to landlines, VoIP and mobile numbers. A single business number typically takes 10–14 working days to port. Mobile numbers can be ported using a PAC code obtained by texting PAC to 65075. Most ports complete with minimal or no downtime for customers.

Every business has at least one phone number customers recognise and trust. It is on your website, your vans, your email signatures and your marketing. The thought of losing it when you change provider can feel risky. The good news is that in the UK you usually do not have to. Thanks to Ofcom's number portability rules, most businesses can keep their existing landline or VoIP number when they switch to a new provider. This process is called number porting.

In a world of cloud phone systems, remote working and the upcoming BT landline switch off in 2027, understanding how number porting works is more important than ever for UK organisations of every size. This guide explains what number porting is, why it matters for future-proofing your communications and the practical steps to get it right with minimal disruption. It also shows how Moneypenny can help you keep the number your customers know, while upgrading to more flexible call handling.

In this article

• What is number porting?
• Why number porting matters for UK businesses in 2025
• How the number porting process works
• How long number porting takes and what it costs
• Mobile number porting and the text to switch rules
• Number porting vs getting a new number: pros and cons
• Common number porting problems and how to avoid delays
• How Moneypenny supports number porting and clever numbers
• Number porting FAQs for UK businesses

What is number porting?

Number porting is the process of moving an existing phone number from one communications provider to another, without changing the number that your customers dial. Ofcom describes it as a regulated facility that lets subscribers change provider while keeping their existing telephone number.

In practice, that means if you are switching from one provider to another and you want to keep your main business number, you ask your new provider to port the number across. They work with your old provider in the background so that, after an agreed date, calls to that number route to your new service instead.

Number porting can apply to:

• geographic landline numbers (for example, 0203, 0161, 029)
• non-geographic numbers such as 03, 08 or 09 ranges
• VoIP or cloud-based business numbers
• mobile numbers, using a slightly different process

Why number porting matters for UK businesses in 2025

Number porting has always been useful, but it is becoming critical for UK businesses because of three big shifts.

1. The BT landline switch off and move to digital voice

BT is switching off the old PSTN and ISDN analogue landline network by January 2027, with many business customers urged to migrate earlier to avoid issues on ageing infrastructure. All landline services will move to all-IP digital solutions, such as VoIP or hosted PBX systems.

For businesses that want to keep the numbers customers already know, number porting is the bridge from traditional lines to modern cloud phone systems.

2. Customers trust the numbers they already recognise

Your phone number appears everywhere, from Google Business listings to invoices. Asking customers to update their records every time you change provider is slow, risky and easy to get wrong. Porting lets you upgrade your phone system or call answering without erasing that hard-earned familiarity.

3. Competition between providers is stronger than ever

Ofcom's portability rules are designed to support competition, so you can switch to a provider that offers better support, features or pricing without losing your number. For businesses using outsourced receptionists or AI voice services, number porting protects your flexibility and bargaining power.

Next step: future-proof your main business number

If you are planning a move to VoIP, outsourced call answering or AI voice, it makes sense to plan your number porting at the same time. Keeping your existing number while upgrading your call handling gives customers a smoother experience. Explore flexible call answering →

How the number porting process works

Behind the scenes, number porting involves both communications providers (CPs) and the network operators (NOs) that carry calls on their behalf. You do not need to be a telecoms expert, but it helps to understand the basics.

1. Choose your new provider
   Pick the provider you want to move to: a VoIP platform, a unified communications provider or a specialist telephone answering service such as Moneypenny. Confirm they can accept ports for your type of number.
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2. Request a port and provide details
   Your new provider will ask for information about your existing line. This usually includes:
   
   • the number or range of numbers you want to port
   • the current provider's name
   • the account name, billing address and account number as they appear on your bill
   • authorisation on headed paper of via a formal letter of authority
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3. Providers agree the porting date
   Your new provider sends a formal porting request to your existing provider. They agree a transfer date. Where a porting agreement is not yet in place, this can add time while a technical route is set up.
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4. The number moves across
   On the agreed date, your number switches from the losing provider to the gaining provider. In most cases, downtime is very short, often a few minutes, and many ports complete without customers noticing at all.

How long number porting takes and what it costs

The time it takes to port a number depends on the type of number, how many numbers are involved and how clean your account data is.

• Single business landline or VoIP number: often around 10–14 working days from a valid request, sometimes quicker
• Large ranges or complex setups: multi-line ISDN, DDI ranges and multi-site ports can take longer and may need extra checks
• International numbers: timelines vary by country and local regulation

Some providers charge an administration fee per number or per range. Others include a certain level of porting in their setup costs. You may also need to pay any early termination fees owed to your current provider if you are leaving before your contract ends.

Mobile number porting and the text to switch rules

Mobile number porting follows a slightly different process, although the principle is the same: you can keep your mobile number when you switch network.

Since 2019, Ofcom's text to switch rules allow you to get a Porting Authorisation Code (PAC) by text, without having to call your existing provider. To keep your number when you move network, you simply text PAC to 65075. Your provider must reply by text, normally within a minute, with your PAC and any important information about early termination charges.

You then give that PAC to your new mobile network, who arrange the transfer. Once the port completes, your old SIM will stop working and your new SIM will take over with the same number.

💡 Moneypenny insight: The PAC code process is one of the smoothest porting experiences available. Most mobile transfers complete within one working day of providing your code to the new network, with no action required on the day itself.

Number porting vs getting a new number: pros and cons

Porting your number is often the best option for continuity, but there are times when choosing a new number can make sense. Many expert guides recommend reviewing both routes before you decide.

Benefits of porting your existing number

• no need to reprint signage, stationery or vehicle branding
• less risk of customers calling the wrong number or thinking you have closed
• better continuity across Google Business listings and online directories
• easier for long-standing customers to recognise and trust your brand

When a new number can be useful

• you want a more memorable or location-specific number to support growth
• you are changing business model or region and want a clean break
• your existing number is heavily targeted by spam or has been misused in the past

Some businesses choose a hybrid approach: they port their existing main number for continuity, then add new regional, national or freephone numbers for campaigns, tracking or specialist teams.

Next step: keep your existing number and add new clever numbers

With Moneypenny's Clever Numbers, you can keep the business number customers already know, while adding new regional, national or freephone numbers that route wherever you need them. Discover Clever Numbers →

Common number porting problems and how to avoid delays

Most ports run smoothly, but there are a few common issues that can delay or block a port if they are not addressed up front.

1. Mismatched account details
   If the details on your porting request do not exactly match your current provider's records, the port can be rejected. Always check the latest bill and confirm the official account name, address and account number before you submit anything.
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2. Active services on the line
   Certain added services, such as broadband or alarm lines, can complicate a port. Your new provider may advise on whether these need to be moved, cancelled or separated before the port goes ahead.
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3. Contract or minimum term issues
   If you are still inside a minimum term, you may face early termination charges from your existing provider. That does not usually stop the port, but you should go in with your eyes open about any costs.
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4. Complex number ranges or international ports
   Large ranges, international numbers or very old allocations sometimes take longer to move. Building extra time into your project plan is wise if your setup is more complicated than a single number at a single site.
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5. Lack of a clear backup plan
   Although downtime is usually minimal, it makes sense to have a backup. For example, you can arrange temporary call forwarding or have a secondary number ready to share with key clients in the unlikely event of a longer outage.

How Moneypenny supports number porting and clever numbers

At Moneypenny, number porting is a familiar part of onboarding. We know how important it is to keep the number customers already know, while upgrading the way calls are answered.

When you move your call answering to us, we will:

• Check whether our providers already have porting agreements in place with your existing carrier
• Guide you through the letter of authority and account detail requirements
• Coordinate the porting date to minimise disruption to your team
• Route calls to our receptionists, AI Voice or your own team according to your preferences

If you decide you would rather start afresh, our business telephone number service lets you choose from a wide range of regional, national and freephone numbers, set up in minutes and routed anywhere you choose. For many SMEs, the ideal mix is keeping their main published number through porting, and adding new numbers for campaigns, tracking or new regions.

Check if your number can be ported by speaking to a member of our team.

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Number porting FAQs for UK businesses

Do I have a legal right to port my business number?‍

Yes. Ofcom's number portability rules are designed so you can change provider while keeping your existing number in most cases. There are some technical exceptions, but it is rare for a port to be refused outright. Your existing provider may still charge contract exit fees if you are leaving early.  

Will I lose service while my number is being ported?

Ports are usually scheduled for a specific date and time window. In many cases, downtime is only a few minutes, and some ports complete so smoothly that users do not notice any interruption. Your new provider can advise on the likely window and any backup options.  

How long does it take to port a business phone number?

For a single UK business landline or VoIP number, a typical port might take around 10–14 working days from the point all correct information is submitted. Complex multi-line or international ports may take longer.  

How do I keep my mobile number when changing network?

Text the word "PAC" to 65075 from the number you want to keep. Your current provider must reply with a Porting Authorisation Code and information about any fees. Give that code to your new provider and they will complete the transfer, usually within one working day of activation.  

Should I port my existing number or get a new one?

If your existing number is well known and widely used, porting it is usually the safest option for continuity. A new number can be useful for fresh branding, campaign tracking or entering a new region. Many businesses choose to do both: port their main published number and add new regional, national or freephone numbers through services like    

Can I port a landline number to VoIP?

Yes. Porting a traditional landline number to a VoIP or cloud phone system is one of the most common porting scenarios, and with the PSTN switch-off in January 2027 it is becoming increasingly important for UK businesses. Your new VoIP provider will handle the technical process; you just need to provide your account details and authorisation.

Can I port multiple business numbers at the same time?

Yes, it is possible to port a range of numbers or multiple numbers as part of a single porting project. Larger ranges and multi-site ports typically take longer to complete and may require additional checks, so it is worth discussing your full requirements with your new provider at the outset and building extra time into your plan.  

What happens if my number port request is rejected?

The most common reason for rejection is mismatched account information: the details on your porting request do not exactly match what is on file with your current provider. Your new provider should tell you the reason for rejection so you can correct the issue and resubmit. In most cases, a rejected port can be resolved quickly once the right information is in place. Technical rejections are less common but your provider will advise on the next steps.  

Can I keep my number if I move offices?

Yes, in most cases. If you are staying with the same provider and moving within the same geographic area, keeping your number is usually straightforward. If you are switching provider at the same time as moving, or moving to a different region, porting is the right solution. With VoIP and cloud phone systems, your number is no longer tied to a physical location, which makes keeping it even simpler regardless of where your team is based.  

Can I port a number from BT to a cloud phone system?

Yes. Porting from BT or any traditional carrier to a cloud phone system or VoIP provider is fully supported under Ofcom's portability rules. Given the upcoming PSTN switch-off in January 2027, many businesses are doing exactly this. Your new cloud provider will manage the porting request on your behalf; you will need to provide your BT account details and sign a letter of authority. The process typically takes 10–14 working days for a single number.  

Does number porting affect SEO or local search rankings?

Porting your number does not change the number itself, so it should not directly affect your SEO or local search rankings. In fact, keeping your existing number through porting is better for local SEO than changing to a new one, because it maintains consistent NAP (name, address, phone) data across Google Business Profile, directories and citations. If you were to switch to a different number, you would need to update all those listings, and inconsistencies during the transition can temporarily affect local rankings.