How to Keep Your Business Phone Number When Switching Provider

Published: 17 March 2026 • Compare The Networks

If you are thinking about switching your business mobile provider, the number one question is almost always the same: “Will I lose my phone number?” The answer is no. You have a legal right to take your existing business phone number with you when you move to a new provider. This guide explains exactly how number porting works for UK businesses, covers PAC codes and STAC codes, walks through the step-by-step process for single lines and bulk ports, and shows you how to avoid the most common porting pitfalls.

Whether you have a single business mobile, a fleet of 50 handsets, or a traditional landline number you want to keep, this guide has you covered. And if you would rather someone else handled the whole process, Compare The Networks manages the porting for you at no extra cost.

Your Legal Right to Port Your Business Number

Number portability is not a courtesy offered by your provider — it is a regulatory requirement. OFCOM’s General Conditions C7 set out clear rules that all UK telecoms providers must follow:

• Your provider must supply a PAC code within one working day of your request. There is no wiggle room on this — one working day is the legal maximum.
• Your provider cannot refuse to port your number. They may try to persuade you to stay (known as “save activity”), but they are not allowed to withhold the PAC code or delay the process.
• There is no charge for obtaining a PAC code. Your provider cannot levy a fee for issuing the code itself.
• The port must complete within one working day of you giving the PAC code to your new provider (for mobile numbers).
• Your number belongs to you, not to your provider. This applies equally to business and personal accounts.

These rules exist because OFCOM recognises that phone numbers are critical business assets. Your customers, suppliers, and partners all know your number. Losing it could mean lost revenue, missed enquiries, and a damaged professional image. The regulations ensure that switching provider never means sacrificing your number.

PAC Code vs STAC Code: Understanding the Difference

When you leave a mobile provider, you have two options — and choosing the wrong one means losing your number permanently. Here is the difference:

For business accounts: always use a PAC code unless you are deliberately dropping a line that is no longer needed. A STAC code should only be used when you genuinely want to retire a number. If in doubt, use the PAC — you can always choose not to use the number on the new provider, but at least you have not lost it.

Text INFO to 85075: Check Your Contract Details Instantly

Before you do anything, there is a quick way to find out exactly where you stand with your current provider. Text INFO to 85075 from any mobile on the account. This is an OFCOM-mandated service that works on all UK networks. Your provider must reply within one working day with:

• Your contract end date — so you know whether you are in or out of contract
• Any early termination charges — the exact amount you would pay to leave early
• How to request your PAC or STAC code — instructions specific to your provider

This is the fastest way to check how long is left on your contract without logging into a portal or calling customer services. For business accounts with multiple lines, you may need to text from each line individually or contact your account manager for a full overview.

Why Loyalty Does Not Pay: Switch and Save

If your business has been on the same mobile contract for years, you are almost certainly overpaying. Here is why:

• Out-of-contract rates are inflated — when your minimum term ends, your provider rolls you onto a Shorter at the same price. But you have already paid off any handset — so you are paying £10–£20/month extra per line for a phone you already own.
• New customer deals are always cheaper — networks reserve their best business pricing for new customers and switchers. Existing customers are rarely offered the same deals unless they threaten to leave.
• Annual price increases compound — with fixed £2.50 + VAT/month increases each April, a plan from 3 years ago now costs £7.50 + VAT more per line per month than when you started. New contracts reset to today’s base price.
• Technology has moved on — plans from 2–3 years ago often have less data, no 5G, and outdated roaming terms. Today’s plans offer more for less.
• There are no loyalty rewards — unlike broadband or insurance, mobile networks do not offer meaningful discounts for staying. The savings come from switching.

Businesses that switch through Compare The Networks typically save 20–40% per line. For a company with 10 lines at £35/month, that is £840–£1,680/year in savings — plus better data, newer devices, and improved coverage. And you keep all your numbers.

How Business Number Porting Works: Step by Step

The process for porting business mobile numbers is straightforward, but it helps to know what to expect at each stage. Here is the complete step-by-step process:

Step 1: Decide Which Numbers to Port

Start by listing every number on your business account. Decide which numbers you want to take to the new provider and which (if any) you want to retire. For most businesses, you will want to port every active number to maintain continuity.

Step 2: Request PAC Codes

For business accounts, you typically cannot use the consumer text-based PAC request system (texting PAC to 65075). Instead, you will need to:

• Call your network’s business support team or contact your account manager directly
• Request PAC codes for all the numbers you want to port
• The provider must supply them within one working day
• Write down every PAC code alongside its corresponding phone number — mixing them up causes port failures

Step 3: Give PAC Codes to Your New Provider

Hand all your PAC codes to your new provider. If you are switching through Compare The Networks, we collect and submit the PAC codes on your behalf so you do not need to worry about the paperwork.

Step 4: Agree a Port Date

You and your new provider agree on a date for the port to take place. For single lines, this is typically the next working day. For bulk ports (multiple lines), you can schedule a specific date that works for your business.

Step 5: Port Day — Brief Interruption

On the agreed port day, there will be a brief interruption to service. This typically lasts 30 minutes to 2 hours. During this window, calls to your number may not connect. The interruption is usually shorter for mobile-to-mobile ports and can be slightly longer for landline ports.

Tip: Schedule your port for first thing in the morning. If anything goes wrong, you have the full business day to resolve it rather than discovering a problem at 4pm on a Friday.

Step 6: Number Active on New Network

Once the port completes, your number is live on the new network. You can make and receive calls and texts immediately. Insert the new SIM card (or activate the eSIM) and you are good to go.

Step 7: Old Contract Automatically Cancelled

When the port completes, your old contract is automatically cancelled for that line. Your old provider will send a final bill, which may include:

• Any remaining charges for the current billing period
• Early termination fees (if you are still within the minimum contract term)
• Outstanding handset balance (if you had a phone on finance)

If the early exit costs are a concern, ask about the CTN Switching Promise — we can cover agreed early termination fees when you switch through us. Terms apply.

Porting Multiple Business Lines

Most businesses do not have just one mobile line. If you have 5, 10, 50, or even 100+ lines, the porting process requires more coordination but follows the same principles.

Bulk Porting: All Numbers on the Same Day

The simplest approach for many businesses is to port all numbers on the same day. This means one brief interruption and then everyone is on the new network simultaneously. The advantages are:

• One transition date to manage
• All employees switch at the same time, avoiding confusion about who is on which network
• New provider can often offer a better bulk deal if all lines migrate together

Staggered Porting: Switch in Batches

For larger fleets or mission-critical operations, staggered porting reduces risk. You might port 10 lines per day over a week, starting with less critical numbers to test the process before moving key personnel. This approach is particularly useful when:

• You have customer-facing lines that cannot afford any downtime
• You want to verify the new network’s coverage and performance before moving everyone
• Your IT team needs time to configure each batch of devices

How CTN Handles Bulk Ports

When you switch through Compare The Networks, we manage the entire coordination. We collect all PAC codes, liaise with the new network, schedule the port dates, and monitor each port to completion. If a port fails (rare, but it happens), we escalate directly with the network’s porting team to get it resolved the same day.

Tip: Always schedule bulk ports for the morning. If a port fails for one line out of 30, having the full working day to resolve it means the employee is not left without a working phone overnight.

Porting Landline Numbers

It is not just mobile numbers that can be ported. If your business has a traditional landline number — the kind starting with 01 (regional) or 020 (London) — you can port it too, and you do not need to keep paying for an expensive BT or Openreach line to do so.

Port to a Virtual Landline

A virtual landline lets you keep your geographic number (the 01 or 020 number that customers recognise) without maintaining a physical telephone line. Here is how it works:

• Your existing landline number is ported to a virtual landline provider
• Calls to that number are automatically forwarded to your mobile phone (or multiple mobiles)
• Callers see and dial the same local number they have always used
• You can set up call routing rules: ring multiple phones simultaneously, set up out-of-hours messages, and more

Cost Comparison: Virtual Landline vs Traditional BT Line

For many small businesses, porting a landline number to a virtual landline saves over £300 per year while actually improving flexibility. Learn more on our virtual landline page.

All prices exclude VAT.

What About VoIP Numbers?

VoIP (Voice over Internet Protocol) numbers — including geographic numbers (01, 02, 03) hosted on a VoIP platform — can usually be ported between VoIP providers. However, the process differs slightly from mobile porting:

• VoIP-to-VoIP ports typically take 5–10 working days
• You will need to provide the losing provider’s details and authorise the port
• Some VoIP providers charge a one-off porting fee (usually £10–£25 per number)
• Non-geographic numbers (03, 08) can also be ported between VoIP providers

Important: VoIP and virtual landline are different products. VoIP is a full phone system (desk phones, apps, call queues, extensions), while a virtual landline is simply a number that forwards to your mobile. They serve different needs, and the porting process may differ. Read our VoIP vs Virtual Landline comparison if you are unsure which is right for your business.

Common Number Porting Problems and How to Avoid Them

While number porting is straightforward in most cases, problems do occasionally arise. Here are the most common issues and how to prevent them:

1. Wrong Account Details

The most frequent cause of port failures is a mismatch between the details you provide and the details held by your current provider. The name on the account, the address, and the account number must match exactly. Even a small difference (e.g., “Ltd” vs “Limited”) can cause a rejection.

How to avoid it: Before requesting PAC codes, call your current provider and confirm the exact account name, address, and account number they have on file. Use those exact details when setting up with the new provider.

2. Expired PAC Code

PAC codes are valid for 30 days. If you do not submit the PAC to your new provider within that window, it expires and you need to request a new one. This is a common issue when businesses take a while to finalise their new contract.

How to avoid it: Do not request PAC codes until you have your new contract agreed and ready to go. If a PAC expires, simply request a new one — your provider must issue it within one working day.

3. Business vs Personal Account Confusion

Some networks have different processes for business and personal PAC requests. If you call the consumer helpline for a business account, you may be directed elsewhere or given incorrect information.

How to avoid it: Always contact your provider’s dedicated business support team. Use the business-specific numbers listed in the table below.

4. Port Rejection

Occasionally, a port request is rejected by the losing provider. This is rare and usually caused by incorrect account details (see point 1 above). Under OFCOM rules, the losing provider must tell you the reason for the rejection within one working day, so you can correct the issue and resubmit.

How to avoid it: Double-check all account details before submitting. If you are using a managed service like CTN, we verify all details before submission to minimise the chance of rejection.

5. Partial Port Failures on Multi-Line Accounts

When porting many numbers simultaneously, it is possible for some ports to succeed while others fail. This can happen if one or two numbers have different account details or are on a different billing account within your business.

How to avoid it: Verify that all numbers are on the same billing account and that the account details match for every line. Using a managed porting service like Compare The Networks reduces this risk significantly because we coordinate with the networks directly and monitor each individual port.

Network-Specific PAC Request Process for Business Accounts

Each network has a slightly different process for business PAC requests. Here is how to request a PAC code from each of the four major UK networks:

Note: For business accounts, the consumer text-based PAC request (texting PAC to 65075) may not work. It is designed for personal accounts. Always call your business support line or contact your account manager directly.

When you call, be prepared for “save activity” — the retention team will try to offer you a new deal to stay. This is standard practice and perfectly legitimate, but remember: they cannot refuse to give you the PAC code regardless of whether you accept their offer.

The CTN Approach to Number Porting

At Compare The Networks, we handle number porting as part of every business mobile switch. Here is what we do differently:

We Collect PAC Codes on Your Behalf

You do not need to spend time on hold with your current provider. We contact them directly, request the PAC codes for all your lines, and handle the paperwork. For businesses with 20, 30, or 50+ lines, this saves hours of phone calls.

We Coordinate the Port Date

We liaise with the new network to schedule the port for a date and time that minimises disruption to your business. We can arrange morning ports, staggered ports, or a full fleet migration — whatever works best for your operation.

We Handle Bulk Ports for Multi-Line Businesses

Bulk porting requires careful coordination. Every PAC code must be matched to the correct number, submitted correctly, and monitored through to completion. We manage this process end-to-end, tracking each individual line through the port.

We Escalate Problems Directly with the Network

If a port fails or is delayed, we do not wait in a call queue. We escalate directly with the network’s porting team through our business channel relationships. This means faster resolution and less downtime for your team.

The Switching Promise

Worried about early exit costs from your current provider? Through the CTN Switching Promise, we can cover agreed early termination fees when you switch through us. This removes one of the biggest barriers to switching. Agreed fees only — terms apply.

Ready to switch and keep all your numbers? Get a free, no-obligation quote and we will handle the entire porting process for you.

Related Reading

• Keep Your Business Number with CTN
• The CTN Switching Promise
• Virtual Landline: Keep Your Local Number
• VoIP vs Virtual Landline: What Is the Difference?
• How to Cancel a Business Mobile Contract

All prices exclude VAT. Fixed £2.50 + VAT/month annual price increase applies each April. Compare The Networks is regulated by OFCOM.