Business phone system migration: replace the old system without losing a number or a day of calls
Switching phone provider worries people for good reason: numbers, contracts and go-live day can all go wrong. Atom IP runs migrations as a defined project, from reading your current contract to parallel running on cut-over day, so the business keeps answering throughout.
Step one: read the contract you have
Before anything is ordered we go through your current agreement for term, notice period, auto-renewal and anything that is equipment finance rather than service. If leaving now would cost more than staying until the right date, we say so and diarise it. That review is free and carries no obligation.
How the migration runs
A phone system change is a sequence, not an event. We design routing and numbering with you, order connectivity if it needs upgrading, pre-configure handsets and apps, then port numbers on a scheduled date with the old system live until the port completes. Larger sites move one team or office at a time.
- Audit of every line, number, circuit and contract on one page
- Design of routing, menus, queues, recording policy and reporting, agreed in writing
- Connectivity and network checked or upgraded ahead of go-live
- Handsets shipped pre-configured; apps rolled out with short guides
- Number porting scheduled with parallel running on the day
- Named engineer through cut-over and the weeks after
Keeping your numbers
UK geographic and non-geographic numbers port between providers. We confirm you are the customer of record, check the port is possible and manage it end to end. The most common cause of a lost number is a contract cancelled before the port completes, which is why we sequence it the other way round.
Legacy lines, alarms and lifts
The PSTN switch-off affects more than phones. Alarm autodiallers, lift lines, door entry and some payment terminals still rely on analogue lines. We survey these alongside the phone system and migrate or replace them so nothing critical is left on a line that is about to be withdrawn.
Not sure which option fits? Ten minutes with an engineer will tell you.
Tell us how many people need a phone, where they work and what you run today. You get a straight answer on options and cost, not a sales script.
Read next
Hosted VoIP: a business phone system that lives in the cloud, not in a cupboard
Hosted VoIP replaces the on-premise PBX with a phone system run from UK data centres. Your desk phones, laptops and mobiles connect over your broadband, and every change is made by an engineer in minutes rather than a site visit.
Read moreMulti-site phone systems: one platform across every office, branch and home worker
Running a separate phone system in each location means separate bills, separate suppliers and calls that cannot be transferred between sites. A hosted multi-site phone system puts every office on one platform with one number plan, one admin portal and one support team.
Read moreSmall business phone systems that make a five-person company sound and work like a bigger one
A small business does not need a smaller phone system; it needs the same professional features without the hardware, the long tie-in or the licence block it will never fill. Atom IP sets up cloud phone systems for UK companies from two users upwards.
Read moreWhat Atom IP customers say
“Good guys — worked with them to switch over from a previous very good supplier. They have gone above and beyond to understand our needs and bespoke systems to help support our specific needs. Transition over on getting their systems up and running was smooth. As a small business owner, trust and confidence are important to me.”
“We have been using Josh at Atom for a few years now. Service has always been amazing. Just today our router blew up due to a power surge and he came out promptly with a new one to make sure we were back online in time for trading. Would highly recommend.”
“There aren’t many telecom providers that can be described as truly honest and straightforward. Georgia was very well spoken and made me feel my company was in the right hands. Ollie and Josh responded promptly throughout getting my phones and security systems set up. The install was seamless with no drop in connectivity and no technical issues since.”
Migration FAQs
Short answers here. An engineer will answer anything specific to your building, team or current contract.
Ask about switching from the engineers who will install it
Roughly how many users, how many sites and what you run today is enough to start. You will hear back from an engineer within one working day.
- Keep your existing numbers, ported from any UK provider
- Contract term, notice period and costs in writing before you sign
- Southampton head office, on site across Hampshire, remote UK-wide
Phone systems alongside the rest of your setup
A phone system only works as well as the broadband under it and the contract around it.
Solutions
All solutionsLocations
All locations- Southampton, HampshireBusiness phones, broadband and IT in Southampton
- Portsmouth, HampshireBusiness phones, broadband and IT in Portsmouth
- Winchester, HampshireBusiness phones, broadband and IT in Winchester
- Bournemouth, DorsetBusiness phones, broadband and IT in Bournemouth
- Basingstoke, HampshireBusiness phones, broadband and IT in Basingstoke
- Reading, BerkshireBusiness phones, broadband and IT in Reading
- LondonBusiness phones, broadband and IT in London
- Guildford, SurreyBusiness phones, broadband and IT in Guildford
Guides and insights
All insights- 4Com Business Phone Contracts: What UK Businesses Should Watch Out For (2026)A frank look at 4Com business phone system contracts — the finance-lease structure, the multi-year commitments, the "upgrade" cycle, and what to check before signing or renewing. Independent, no affiliation.
- Zappie Communications Ltd Has Entered Liquidation — What UK Businesses Should Do NextZappie Communications Ltd has entered formal liquidation. If your business phone system, VoIP or broadband was sold to you under the Zappie brand, here is what to check, what to avoid, and how to protect your numbers, contracts and continuity.
- Basingstoke Business Phone System, VoIP and Broadband: A 2026 Buyer's GuideBasingstoke business phone system and business broadband options in 2026 — cloud VoIP, hosted PBX, SIP trunking, Microsoft Teams calling, business FTTP and leased lines across RG21–RG29.
- SIP Trunking vs Hosted VoIP: Which Business Phone System Approach Is Right?A UK buyer's guide to SIP trunking, hosted VoIP, hosted PBX and cloud phone systems in 2026 — technical differences, prices, pros, cons and how to choose the right business phone system for your company.