How to port a business phone number without losing calls

Porting a business phone number means moving an existing number to a new provider without changing the number itself. It typically takes 1-7 working days in the UK, or 1-4 weeks in the US. The exact time depends on whether it’s a mobile, landline, or VoIP number. The process itself is simple on paper: request the port, confirm your identity, wait.

Most delays come from mismatched account details, not the technology itself. Here’s what to check before you start, and a checklist to run through so your number doesn’t go dark mid-port.

What porting actually is

Number porting transfers your phone number from your current carrier to a new one while keeping the number itself unchanged. The new provider takes over routing calls to that number; your old provider releases it once the transfer is confirmed. You don’t need a new number, and customers who already have your number don’t need to be told anything changed.

UK timescales: 1-7 working days

Porting rules and available number formats for UK numbers differ slightly from the US process below, mainly around who verifies the account.

Ofcom’s rules require simple mobile-to-mobile ports to complete within one working day once you’ve supplied your PAC (Porting Authorisation Code). This has been a standard since 2010 (Ofcom, “Changes to the Mobile Number Porting Process”).

Business landline and VoIP number ports, however, commonly run longer in practice, often 5-7 working days. That’s because they involve range holders and back-end carrier checks, rather than a single mobile-to-mobile handoff.

Practical steps for a UK port:

1. Request your PAC (mobile) or account/porting details (landline/VoIP) from your current provider.
2. Give the PAC or number/account details to your new provider.
3. Confirm the port date. Mobile ports are typically same-day or next working day; landline/VoIP ports are usually scheduled 5-7 working days out.
4. Keep your old SIM or line active until the new provider confirms the port has completed.

US timescales: 1-4 weeks

The rules below apply to US numbers generally, though carrier-specific processes vary. The FCC requires simple wireless-to-wireless ports to be processed within one business day. In practice, business number ports commonly take 1-4 weeks, especially for landline-to-VoIP or multi-line business accounts. They require more validation steps between carriers, and often involve a Letter of Authorization.

Practical steps for a US port:

1. Gather your account number, PIN/passcode, and the exact billing name and address on file with your current carrier.
2. Sign the Letter of Authorization (LOA) your new provider sends, matching your account details exactly.
3. Submit the port request and track its status with the new provider.
4. Keep paying your old provider’s bill until the port confirms complete, since an unpaid balance can freeze the number mid-transfer.

LOA and PIN gotchas

The single most common reason a port stalls is a mismatch. What’s on the LOA doesn’t match what the losing carrier has on file. A business name typed slightly differently, an old address still listed, or a PIN that’s since been reset will all reject the port automatically. There’s no explanation beyond “rejected.”

Common gotchas to check before submitting:

• The billing name on the LOA must match the losing carrier’s account exactly, including “Ltd”, “LLC” or punctuation.

• The account PIN or passcode must be current. If you’ve never set one, request it from your carrier before starting, since some carriers won’t let you port without it.

• The account must be active and in good standing. A frozen or suspended account (usually from an unpaid balance) will block the port until resolved.

• Fax-to-email and forwarded numbers sometimes can’t be ported at all. Check with your losing carrier if your number was ever set up as a virtual forward.

• Toll-free numbers in the US route through a separate Responsible Organization (RespOrg) system. They can move faster than local numbers once authorized, sometimes within days.

None of these gotchas are exotic. They’re the same handful of checks a competent losing-carrier support agent would run through anyway. That’s exactly why gathering the details yourself before submitting the port saves the most time.

Comparing UK and US porting

	UK	US
Mobile-to-mobile	1 working day	1 business day (simple ports)
Landline/VoIP business number	5-7 working days	1-4 weeks
Authorization needed	PAC code	LOA + account PIN
Main failure point	Wrong PAC/expired code	Name/address mismatch on LOA

What happens on the day of the port

For mobile ports, the switch is usually invisible. Your phone briefly loses signal for a few minutes while it re-registers on the new network. Then calls and texts start arriving as normal. For landline and VoIP business ports, the cutover is typically scheduled for a specific time window. This is often overnight or early morning, when call volume is lowest. A brief gap in service is normal and expected, not a sign something’s gone wrong.

It’s worth telling anyone answering phones for the business what day the port is scheduled. That way, a short gap in service doesn’t get mistaken for a technical fault worth troubleshooting mid-morning. Most providers will also confirm completion by email or in-app notification. That’s the point at which it’s safe to fully decommission the old service.

Pre-port checklist

Before requesting any port, confirm a few things. Your account should be active and paid up. You should also have the exact billing name and address the losing carrier has on file. Know your PIN (or be able to get one quickly), and have a fallback way to receive calls, like a temporary forward, if the port takes longer than expected. Use our number porting checklist tool to walk through this step by step before you submit anything.

What to do if the port deadline slips

Ports occasionally run past their estimated window. This is usually because of a rejected LOA that needs resubmitting, or a carrier-side queue delay, rather than anything you’ve done wrong. If a port is running late, contact your new provider first. They’re the ones actively tracking the request with the losing carrier, and can usually tell you exactly which step it’s stuck on.

Keep your old service active throughout any delay. The temptation to cancel the old line once you assume the port has gone through is the single most common cause of an actual outage. This is different from just a delayed but otherwise uneventful transfer.

FAQ

Will I lose calls while my number is being ported?

Not if you keep your old line active until the new provider confirms the port is complete. Most failed ports happen because someone cancelled the old service too early, not because of a gap in the porting process itself.

Can I port a number that’s still under contract?

Usually yes, though you may owe an early termination fee to your current provider. Porting the number and cancelling the contract are separate actions.

What is a PAC code and do I need one for a landline?

A PAC (Porting Authorisation Code) is required for UK mobile-to-mobile ports. Landline and VoIP business ports use different account-based verification instead, not a PAC.

Why did my port get rejected?

Almost always a details mismatch: the name, address, account number or PIN submitted doesn’t match what the losing carrier has on record. Double-check your last bill against what you submitted.

Can I port a number to wlur?

Yes, wlur supports free number porting in and out. Start a 7-day free trial, no card needed, to try it.