Guide to Business Number Porting

Your business number is a core part of your brand identity; it appears on all your marketing materials, exists in directories, and even contributes to your local search engine rankings. With the Public Switched Telephone Network (PSTN) switch-off scheduled for 2027, over 63% of startups have already moved to internet-based phone systems. But how can you retain your precious phone number when moving to VoIP?

Thankfully, UK regulations, overseen by Ofcom, protect your right to keep your phone number when switching providers. In this guide, we’ll walk you through the number porting process, show you how to avoid common problems, and help ensure your business stays connected throughout the transition.

Key Takeaways

• You’ll need to know exactly how the UK porting process works, especially with the upcoming switch from traditional phone lines.
• Ofcom guarantees your right to keep your business phone numbers when changing providers – it’s the law.
• Successful porting needs three key elements: a capable new provider, accurate paperwork (including your port request), and clear communication with your current provider.
• To avoid delays, double-check all account details, review any contract obligations (including possible termination fees), and select VoIP providers that have proven they can handle porting smoothly.

What Is Business Number Porting?

Business number porting lets you keep your existing phone number when you switch from one telecom provider to another.

You might want to move your traditional landline number to a modern VoIP platform in anticipation of the PSTN switch-off, or to cut costs and access better features. Or perhaps you’re already using VoIP but want to switch providers for improved service or pricing.

There’s a difference between number porting and similar services you might have heard of:

• Porting permanently transfers your number to a new provider’s network – your number actually changes hands.
• Diverting or forwarding simply redirects calls from your original number to a different one. Your original provider still owns and controls the number.

Only porting gives you full control of your number with your new provider, creating a permanent solution rather than a temporary workaround.

Why Businesses Port Their Numbers

Businesses port their numbers for several practical reasons that affect their bottom line, customer service, and overall operations:

• Finding a better VoIP deal: The VoIP market offers plenty of options, and you can often save substantial money on call charges and monthly fees by switching. Many businesses also switch to improve reliability and service quality when their current provider isn’t meeting expectations.
• Going all-in on unified communications: Modern unified communication systems bring together voice calls, video meetings, messaging, and team collaboration in one platform. Porting your existing number to a unified communication system lets you enjoy the benefits of VoIP without forcing customers to learn a new number.
• Moving premises but keeping your local presence: If your business relies on local customers, keeping your area code matters even when relocating. Number porting means you can maintain your Manchester number even if you move to Leeds, for example, preserving that local connection customers trust.
• Saving on marketing materials: Changing your phone number means updating every business card, brochure, website, and directory listing – an expensive and time-consuming process. Porting eliminates this hassle completely.
• Preserving brand recognition and search rankings: Your existing phone number has likely built up recognition and trust over time. Changing it risks losing these valuable assets.

Types of Numbers You Can Port

Most UK business phone numbers can be ported, giving you flexibility when switching providers. Here’s a breakdown of what you can port:

Before starting any switch, confirm with your new provider that it can port your specific number type. Most reputable VoIP companies can handle all standard business numbers without problems.

Number Porting and VoIP in 2025

Many leading VoIP providers now offer smart transitional solutions like ‘instant porting’ or ‘partial porting’. These clever workarounds let you start using your new VoIP system right away, with calls to your old number temporarily forwarded to a provisional number on your new system. You get immediate access to new features while the formal porting process happens behind the scenes.

Your current setup affects how the port works. If your number runs on a SIP trunk, traditional PBX, or hybrid system, the technical process will vary. Good VoIP providers can handle all these scenarios, but you should explain your current setup in detail to avoid surprises.

Expert tip: Ask your new provider how it handles your specific setup. For example, if you’re porting from a multi-line PBX, check whether the provider can port your entire number range in one go or if it will need to handle each line separately.

How Business Number Porting Works: Step-by-Step

Number porting follows a straightforward sequence, though being aware of potential pitfalls at each stage will help ensure a smooth transition. Here’s exactly what happens:

1. Choose a new provider

First, you’ll need to find and select a new VoIP provider that meets your needs and can port your existing number. Look beyond just price; consider the features you need, the customer support reputation, the reliability record, and how experienced the provider is with porting.

Expert tip: Ask potential providers about their specific experience porting numbers like yours. Some have more expertise with certain number types or from specific carriers. Providers with dedicated porting teams typically handle the process more efficiently.

2. Request a porting form (LOA, aka Letter of Authority)

After signing up with your new provider, you’ll need to initiate the actual number porting request. Your new provider will give you a Letter of Authority (LOA) form to complete. This document grants permission to contact your current provider and transfer your number on your behalf.

Potential delay: Incomplete or invalid LOAs are immediate grounds for rejection. Ensure all required fields are completed, the form is signed by an authorised representative, and you’re using the current version of the form supplied by your new provider.

3. Submit documentation (matching old account details)

When filling out the LOA, every detail must match exactly what your current provider has on record – your legal business name, billing address, and service address for the phone number. You’ll usually need to provide a recent bill from your current provider as supporting documentation.

Expert tip: The most common causes of porting delays and rejections are small discrepancies like ‘Ltd’ versus ‘Limited’ or ‘St’ versus ‘Street’. Before starting the porting process, call your current provider to confirm exactly how your business name and address, or addresses, appear in its system, then use this precise information on your forms.

4. Wait for validation from your old provider

Once your new provider submits your port request, your current provider will check that all the information matches its records. It will either approve the port (if everything lines up and your account is in good standing) or reject it (if it finds discrepancies or outstanding issues). This validation typically takes two to five business days.

Potential delay: If you’re still under contract with your current provider, you might need to pay a termination fee to release your number. While Ofcom rules prevent providers from blocking ports due to unpaid bills, contract obligations are different and should be reviewed before initiating the port.

5. Schedule a port date

After approval, your new provider will work with you to set a date and time for the actual transfer. Most providers recommend scheduling the port outside business hours – evenings or weekends – to minimise any disruption.

Timing tip: Avoid scheduling ports immediately before major holidays or during peak holiday periods when staffing at either provider might be reduced, as this can add days or even weeks to the process.

6. Test and verify the port on completion

When the scheduled port date arrives, your number will transfer from your old provider to your new one. As soon as the port completes, test the line thoroughly. Make test calls from different phones to your number and place outbound calls from your system.

For a standard single UK geographic number, expect the entire process to take about seven to 10 working days from submitting your paperwork. Multi-line systems, non-geographic numbers (like 0800 or 0845), or complex setups may take longer.

Best practice for a smooth port:

• Triple-check all details against your current provider’s records before submission
• Maintain both services during the transition period
• Choose a provider with proven porting experience and dedicated support
• Document all communications related to the porting process

Your Rights: Ofcom Rules on Number Portability

UK businesses have a legal right to keep their phone numbers when switching providers – it’s guaranteed by Ofcom regulations.

Ofcom created these rules to protect business and consumer choice. Without number portability, many companies would stay with poor-performing or expensive providers simply to avoid losing their established phone numbers.

While providers often quote seven to 10 working days as standard for porting, the official Ofcom guidance requires them to complete ports as soon as is reasonably practicable and on reasonable terms.

Several industry organisations help implement Ofcom’s number portability framework. These include:

• NICC: Develops the technical standards that make number porting possible between different networks
• OTA2: Oversees cooperation between competing communications providers
• MNP OSG: Focuses specifically on mobile number portability arrangements

If you hit roadblocks during your porting process, check Ofcom’s number portability page for guidance. Your provider can’t unreasonably refuse or delay your port request. Knowing your rights helps ensure they’re properly respected and can significantly reduce the stress and potential disruptions associated with switching telecom services.

Don’t Let Number Porting Hold Back Your Migration

Concerns about number porting shouldn’t stop you from upgrading to better, more affordable communication systems. The benefits of keeping your existing number when switching to VoIP – maintaining your brand recognition, preserving customer connections, and retaining any SEO value – outweigh the effort involved.

With proper planning, the process becomes manageable. We’ve evaluated providers based on their porting support, customer feedback, and overall value. Our comparison tools let you find options that match your specific needs while keeping the number your customers already know.