The only expensive way to switch business telecoms is in a rush. Give yourself six weeks and you'll switch invisibly; do it in a fortnight and you'll take calls on your mobile in a coffee shop. Here's the timeline that actually works.
Step 1: Check your contract end date
Most UK business telecom contracts auto-renew. You usually need to give 30 days' notice — miss that window and you're locked in for another 12–36 months.
Dig out the original signed contract or ask your account manager in writing for the exact end date and notice period. Verbal confirmation isn't good enough — providers regularly claim different dates when it costs you money.
Step 2: Switching broadband without downtime
For fibre-to-fibre migration on the same Openreach line, most providers handle a hot-swap: your existing line switches to the new provider on a set date, no engineer visit.
For a new line install (FTTP where you had FTTC, or a leased line), book the install with a 1–2 week overlap. Never cancel the old line before the new one is confirmed live.
Ask the new provider whether the switch is a same-line transfer or a fresh install — the answer dictates the timeline.
Step 3: Porting VoIP numbers
Number ports take 5–10 working days once initiated. Submit the port request to your new provider with a recent bill showing the number and the account holder's name.
Run old and new systems in parallel during the port window. Set up call forwarding from the old system to the new numbers so nothing is missed.
Test outbound calling, inbound calling, voicemail, and call recording on the new platform before you cut the old one.
Step 4: Switching business mobiles
Request PAC codes for each number from your current network — legally they must provide them within one working day.
Order the new SIMs first. Activate them the moment they arrive by entering the PAC. Ports happen the next working day.
Do phones one at a time for critical staff, or in batches by team for larger fleets. Never port a whole company on the same day.
Step 5: Cutover day
Do the switch on a Tuesday, Wednesday or Thursday morning — never a Friday. If something breaks you have the rest of the week to fix it with the new provider's full support desk staffed.
Have the old provider's support number to hand until you've been on the new one for a full billing cycle without issues.
Frequently asked questions
Will my business have downtime when switching broadband?
Not if you plan it. Same-line migrations are usually zero-downtime. New installs need 1–2 weeks of overlap so the new line is live before you cancel the old one.
How long does it take to port a UK business phone number?
5–10 working days once the port is submitted. Larger port batches (20+ numbers) can take longer — always run old and new systems in parallel until the port completes.
What's a PAC code and how do I get one?
A Porting Authorisation Code lets you move a mobile number to a new network. Text PAC to 65075 or ask your current provider — they must issue it within one working day by law.
Can I switch broadband mid-contract?
Only by paying an early termination fee, which is usually the remaining monthly line rental. Time your switch to your contract end date wherever possible.
How much notice do I need to give my current telecom provider?
Typically 30 days in writing. Some providers require 90 days for leased lines. Check your original contract — verbal confirmation from account managers is not reliable.