How to port your UK phone number to VoIP (PAC and STAC explained)

PAC, STAC, and the timelines that actually apply. The exact steps to move a UK landline or mobile number to a VoIP provider without losing a call.

UK number portability is a regulator-mandated right. You can move any UK landline or mobile number between providers within 24 hours, free of charge.

Landline porting (STAC)

  1. Request your STAC code from your current provider (free, within 1 working day).
  2. Supply the STAC and the billing address that matches your current bill to Silux Call.
  3. We submit the port. Cut-over typically completes within 24 hours.
  4. Test inbound and outbound from your existing DDI on Silux Call.

Mobile porting (PAC)

Mobile porting uses a Porting Authorisation Code (PAC). Text PAC to 65075 on your old SIM. Give the PAC to Silux Call within 30 days.

Common gotchas

  • Outstanding contract — your old provider must clear early-termination fees first.
  • Address mismatch — keep the old bill address until the port completes.
  • Multi-DDI ranges — port the whole range with one submission, not one at a time.

Other guides

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