A valid UK mobile PAC switch should normally complete within one working day after the new provider accepts the code, unless you agree to a later date.
Working day matters
Weekends and public holidays can affect scheduling. A code submitted late in the day may be processed on the next working day according to the provider’s cut-off and instructions.
What can happen during the port
- The old SIM stops first and the new service takes over shortly afterwards.
- Calls, SMS and data may return at different moments.
- The phone may need a restart or brief aeroplane-mode refresh.
- Voicemail and messaging registration can take additional time.
- A split port can route incoming and outgoing services differently and requires support.
When to contact the provider
Contact the new provider if the promised date has passed, the number is wrong, incoming calls still reach the old SIM, SMS fail, or service remains split. Provide the PAC submission reference, date, examples and timestamps.
Compensation and evidence
Ofcom says customers are entitled to reasonable compensation if the switch takes more than one working day or the process is abused. Keep records and use the provider’s complaints procedure if the issue is not resolved.
Do not confuse activation with porting
The new SIM can activate with a temporary number before the old number is moved. The one-working-day porting expectation applies after the new provider accepts the valid code, not necessarily from the moment the SIM is ordered.
Ask for the intended port date and keep the temporary number only as a reference; do not distribute it unless the provider confirms it will remain.
A practical proof before relying on the result
Treat the quoted completion date as a service commitment, not as a reason to dismantle the old setup early. Keep both lines, note when the new provider accepted the code and test each service separately. If the promised working day passes, ask the new provider to investigate and explain its compensation route.
- Record the acceptance time and scheduled date.
- Check calls, SMS, data and voicemail independently.
- Do not cancel the old line manually while the port is active.
Official sources
Facts checked: 25 July 2026. Coverage, device support, plan rules and menu paths can change. Recheck your exact phone, software version, network and plan before acting.
