The honest answer is: three to eight weeks, depending on your starting point. Anyone promising a next-day switchover is either skipping the port process or setting you up for a bad experience.
A realistic timeline
- Week 1: discovery — audit of lines, users, features, call flows, integrations.
- Week 2: design and pricing — call routing plan, hardware list, integration scope.
- Week 3: contracts and letter-of-authority for number porting.
- Week 4: platform provisioning, users created, handsets configured.
- Week 5: pilot with a small group of users, iron out any config issues.
- Week 6: port date agreed, on-site day booked.
- Week 7: port day, cutover, on-site engineer support.
- Week 8: post-go-live handholding, training, tuning.
What can shorten it
- Small business (under 10 users), single site, no integrations — 3–4 weeks is realistic.
- Numbers already on a VoIP carrier (VoIP-to-VoIP port, not PSTN-to-VoIP).
- No handset changes needed — softphone-only rollout.
What lengthens it
- ISDN lines on a legacy carrier — porting takes longer.
- Complex integrations (bespoke CRM, contact-centre features).
- Multi-site with different porting dates per location.
- Existing equipment finance that has to run out before you can move.
Atom IP builds a written migration plan for every UK business we onboard — dates, owners, risks, no jargon.
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