Number porting in the UK is governed by Ofcom regulations. In theory, it should take 1 business day for geographic numbers. In practice, it takes 5-10 days, and things go wrong more often than they should.
After managing 500+ UK number ports, here is the honest guide.
UK Porting Timelines (Real, Not Marketing)
| Number Type | Ofcom Target | Actual Average | Worst Case I Have Seen |
|---|---|---|---|
| Geographic (01/02) | 1 business day | 5-7 business days | 21 business days |
| Non-geographic (03) | 1 business day | 5-7 business days | 14 business days |
| Mobile (07) | 1 business day | 1-2 business days | 5 business days |
| Toll-free (0800/0808) | Varies | 10-15 business days | 30 business days |
Mobile porting is fast because Ofcom enforces it strictly. Geographic porting is slower because the process involves multiple carriers and there is less enforcement pressure.
The 5 Things That Delay UK Ports
1. Account Name Mismatch
The name on your current phone account must match the Letter of Authority exactly. "DialPhone Ltd" vs "DialPhone Limited" vs "Dial Phone Limited" — any variation causes rejection.
Fix: Call your current provider and ask: "What is the exact account holder name on file?" Use that exact spelling on the LOA.
2. The Losing Provider Stalls
Some providers drag their feet on porting. They have 10 business days to respond to a port request. Some use all 10 days, then reject on a technicality, forcing you to resubmit.
Fix: Submit the port request as early as possible. If rejected, resubmit immediately with corrections. Document everything — if the losing provider is deliberately obstructing, you can complain to Ofcom.
3. Number Range Issues
Some older number ranges require "range holder" approval before porting. This adds 3-5 business days to the process because the range holder (often BT Openreach) must confirm.
Fix: Ask your new provider to check the range holder before submitting the port. This identifies potential delays early.
4. Multiple Carrier Hops
If your number has been ported before (e.g., from BT to TalkTalk to your current provider), the routing chain is longer. Each hop in the chain must be updated during porting.
Fix: Nothing you can do except allow extra time. Numbers that have been ported 3+ times sometimes take 10-15 business days.
5. ISDN to VoIP Conversion
If your current numbers are on an ISDN30 circuit, porting to VoIP requires converting from ISDN to SIP. This is technically a "cease and re-provide" rather than a simple port, and it takes longer.
Fix: Ask your new provider if they handle ISDN-to-SIP conversions. DialPhone has a dedicated team for ISDN migrations and provides temporary numbers during the transition.
The Zero-Downtime Porting Strategy
| Step | Timeline | Action |
|---|---|---|
| 1 | Day 1 | Sign up with new provider, get temporary numbers |
| 2 | Day 1-5 | Configure new system on temporary numbers |
| 3 | Day 5-7 | Test everything thoroughly |
| 4 | Day 7 | Submit port request |
| 5 | Day 7-17 | Port processes (old system still works) |
| 6 | Port day | Numbers switch to new system |
| 7 | Day +1 | Verify all numbers work on new system |
| 8 | Day +5 | Cancel old service |
The key: set up and test on temporary numbers BEFORE porting. Your old system stays live on your real numbers until the port completes. Zero downtime.
DialPhone provides free temporary UK numbers during the porting period and assigns a porting specialist who manages the entire process with your losing provider.
