How to Port Your Phone Numbers to a VoIP System

What Is Number Porting?

Number porting is the process of transferring your existing business phone numbers from one provider to another. When you switch to a hosted VoIP phone system, you do not need to change your phone numbers — they move with you. This means your customers, suppliers and contacts continue to reach you on the same numbers they have always used.

Porting is a regulated process overseen by Ofcom, and all UK telecoms providers are required to support it. Whether you are moving from a traditional landline, ISDN or another VoIP provider, your numbers can almost always be transferred.

The Number Porting Process

Here is how the process works when you switch to VoIP with Connection Technologies:

Step 1: Provide Your Number Details

Give your new VoIP provider a list of all the phone numbers you want to port. You will also need to provide:

Your current provider name
Your account number or reference with the current provider
A recent bill showing the numbers (in some cases)
Authorisation to port (a simple signed form)

Step 2: Port Request Submitted

Your new provider submits a formal porting request to your current carrier. This is handled entirely by Connection Technologies on your behalf — you do not need to contact your old provider yourself.

Step 3: Porting Window (5–10 Working Days)

The standard porting window for UK phone numbers is 5–10 working days. During this period, your old service continues to work normally. On the agreed porting date, your numbers are switched to your new VoIP platform, usually with minimal or no downtime.

Step 4: Go Live

Once the port is complete, all calls to your existing numbers are routed through your new VoIP system. You can verify everything is working correctly and your old service can then be cancelled.

What Numbers Can Be Ported?

The vast majority of UK phone numbers can be ported to VoIP:

Geographic numbers (01 and 02) — local area code numbers, the most common type for businesses
Non-geographic numbers (03) — national rate numbers often used by larger organisations and charities
Freephone numbers (0800 and 0808) — free-to-call numbers popular for sales and customer service lines
Mobile numbers — in some cases, mobile numbers can also be ported to a VoIP system

Numbers that typically cannot be ported include some very old number ranges and numbers provided by certain niche carriers, but these situations are rare.

Important Tips for a Smooth Port

Follow these guidelines to ensure your number porting goes smoothly:

Do Not Cancel Your Old Service First

This is the most important rule. If you cancel your old phone service before the port completes, you may lose your numbers permanently. Your old service must remain active until the porting process is finished.

Check Your Contract Terms

Review your existing contract for any early termination fees. While you have the legal right to port your numbers at any time, you may still owe remaining contract payments to your current provider. Factor this into your migration planning.

Allow Enough Time

Do not leave porting to the last minute. Start the process at least 2–3 weeks before your desired go-live date to allow for any delays or complications.

Verify Number Ownership

Ensure the numbers are registered in your business name with your current provider. Discrepancies in account details can delay the porting process.

Common Issues and How to Avoid Them

Rejected port requests — usually caused by incorrect account details; double-check all information before submitting
Delayed ports — occasionally the losing provider is slow to process; your new provider can chase this on your behalf
Partial ports — if you only want to port some numbers from a range, make this clear upfront
Service overlap — plan for a brief period where both old and new services are active to ensure no calls are missed

Connection Technologies Handles Everything

When you keep your business number and move to VoIP with Connection Technologies, we manage the entire porting process for you. From submitting the initial request to coordinating the switchover date, our team ensures a smooth transition with minimal disruption to your business.

Ready to port your numbers to VoIP? Get a free quote and we will include number porting as part of your migration plan.