Most mobile-number ports complete without intervention, but a split service, rejected PAC or delayed SMS route needs precise evidence and action from the new provider rather than repeated phone resets.
Identify the exact failure
| Symptom | Most useful first check |
|---|---|
| PAC rejected before a date is booked | Check the code, expiry date, number and whether the request is with the correct losing provider. |
| Temporary number still shows on outgoing calls | Confirm the accepted port date with the new provider and restart once after the stated completion time. |
| Incoming calls reach the old SIM | Treat this as a possible split port and report examples to the new provider. |
| Calls work but SMS or bank codes do not | Record the sender, time and direction; SMS routing can finish separately. |
| Mobile data fails after the number moves | Check line selection, account provisioning and APN before changing the eSIM. |
| Voicemail is missing or behaves differently | Set it up again with the new network after the port is complete. |
Before contacting support
- Keep both SIMs or eSIM-capable phones available.
- Write down the PAC, date submitted and promised port date.
- Test an outgoing call, an incoming call from another network, outgoing and incoming SMS, data and voicemail separately.
- Take screenshots of the number shown in the phone settings and provider account.
- Do not delete the new eSIM or factory-reset the phone unless the new provider gives a specific reason.
Who must investigate
The new provider normally owns the switch after it accepts the PAC. Give it exact examples rather than saying only that “the port failed”. If calls route differently in each direction, use the words possible split port. The new provider can coordinate with the losing provider; the customer should not be sent back and forth without a case reference.
Delayed ports and compensation
Ofcom requires a correctly initiated switch to complete within one working day unless a later date is agreed. Where a provider delays the port, reasonable compensation may be due. Ask the new provider to record the missed date and explain its compensation process. Ofcom does not resolve individual billing disputes, but its guidance and complaint route can help when a provider blocks or delays number porting.
Protect access while the route is unstable
Avoid repeatedly requesting security codes during the transition. Use recovery codes or app-based approval where available, and postpone a port if it would coincide with travel, a banking deadline or loss of access to the old device. Once routing is stable, verify a small number of important services.
The final check that prevents the common mistake
Diagnose a port by direction: outgoing caller ID, incoming calls, outgoing SMS, incoming SMS, voicemail and data can complete at different times. Record examples with times and the networks involved. A split port is owned by the new provider after it accepts the transfer; deleting an eSIM or resetting the handset can destroy useful evidence.
- Test from at least one number on another network.
- Keep both old and new SIMs until the provider confirms completion.
- Escalate with the promised date and case reference.
Official sources
Facts checked: 25 July 2026. Rules, plan features and menu paths can change. Recheck the current terms for your exact provider, plan and device before acting.
