If your business has more than one location, a multi site phone system can make a big difference to how calls are handled. Instead of each branch having its own separate lines and phones, every office joins one system. Calls can be transferred between sites, busy branches can share the load and everything is managed in one place. This guide explains how it works and what to consider.
It’s written for UK businesses with roughly 8 to 50 staff spread across two or more offices, branches or practices.
The problem with separate phone lines at each site
Many growing businesses add a branch and simply order a new phone line for it. Over time, that leads to a patchwork of separate systems, contracts and numbers. Common frustrations include:
- Transferring a caller to another branch means giving them a different number to ring.
- Calls between offices are charged as external calls.
- One branch is overwhelmed while another is quiet, with no way to share calls.
- Each site has different phones, voicemail and opening-hours messages.
- Nobody can see call activity across the whole business.
- Several contracts and bills to manage.
How a multi site phone system works
A hosted phone system runs in a secure data centre and connects to every office over the internet. Each site, and each member of staff, connects to the same system. Our hosted PBX page covers the basics.
One extension plan
Every user gets an extension number. You can arrange these by site, for example 2xx for one office and 3xx for another, so staff can call any colleague directly regardless of location. Calls between extensions are internal.
Keep each branch’s local number
Customers often know a branch by its local number, so most businesses keep them. Each number can ring its own branch, a central team or both. Number transfer is free, and you can add new numbers when you open new sites.
Transfers between offices
If a caller needs someone at another site, staff transfer the call by extension, just as if they were in the same building. The caller stays on the line and doesn’t need to redial.
Sharing calls across branches
One of the main benefits of a multi site phone system is flexibility over who answers.
- Overflow: if nobody answers at one branch within a set time, the call rolls over to another branch or a central team.
- Central reception: one team can answer the main numbers for all sites and pass calls on.
- Lunch and holiday cover: a quiet branch can cover calls for a short-staffed one.
- Out-of-hours rules: all sites can share one out-of-hours message or on-call route, or each can have its own.
Consistent customer experience
With all branches on one system, you can use the same greetings, hold music and voicemail approach everywhere, while still letting each branch use its own name. Customers get a consistent experience wherever they call.
Visibility and reporting
Call reports cover every site, so you can compare call volumes, answered calls and missed calls between branches. That helps with staffing decisions, especially when opening a new location or reviewing a quieter one.
Staff working between sites or from home
Managers who move between branches keep the same extension wherever they are. With the desktop or mobile app, they can also take calls from home or on the road. When someone moves to another branch, their extension simply moves with them. No engineer visit is needed.
Which businesses benefit most?
Multi-site phone systems are especially useful for:
- Estate and letting agents with several branches and an out-of-hours repair line.
- Accountants and solicitors with more than one office.
- Dental and medical practices working across sites.
- Recruitment agencies with regional offices.
- Businesses that have merged and inherited different phone systems.
Common questions before switching
Business owners with several sites often worry that moving to one system will be complicated or disruptive. In practice, most of the work happens before switch-over day. The new system is built and tested in advance, numbers are transferred at an agreed time, and staff are shown how to use their phones and apps before they need them.
Another common concern is what happens if one site’s internet connection goes down. With a hosted system, calls to that branch can be redirected to another site or to staff mobiles, so customers can still get through while the connection is fixed. This is one advantage over separate on-site systems, where a fault at one office often means its phones simply stop working.
It’s also worth thinking about growth. When you open a new branch, adding it to a hosted system means connecting phones or apps for the new staff, plus any new local number. There’s no need to buy a separate phone system for each new office.
Moving several sites without disruption
Migrating more than one office takes planning. A typical approach is:
- Audit: list every number, line, phone and piece of equipment at each site, including alarms or card machines that use a phone line.
- Design: agree the extension plan and call flows for each branch.
- Check connections: make sure each site’s internet connection is suitable.
- Phase the move: switch sites one at a time, or all at once, whichever suits your business.
- Support: make sure help is available on and after switch-over day.
Our PBX migration service explains how we move businesses from older phone systems.
The PSTN switch-off and multi-site businesses
The UK’s traditional phone network and ISDN lines are being retired, with a switch-off deadline of 31 January 2027. Multi-site businesses often have the most old lines to replace, so starting early helps. It’s also a natural moment to bring every branch onto one system rather than replacing lines one by one.
What it costs
Our business phone system is priced from £13.49 per user per month on yearly billing, or £14.99 per user per month on monthly billing. There’s no separate charge per site for the system itself. You pay for the users. For example, 18 users across three branches would cost from about £242.82 a month on yearly billing.
We support businesses across the UK, including in Birmingham, Nottingham and Glasgow.
To plan a phone system for your branches, call 0333 307 3500 or request a quote.
Frequently asked questions
Can each branch keep its own phone number?
Yes. In most cases, every existing number can be transferred, and number transfer is free. Each number can ring the branch, a central team or both.
Are calls between our offices free?
Calls between extensions on the same system are internal calls, so staff can call colleagues at any site by extension.
Can one receptionist answer calls for every branch?
Yes. Calls to any branch number can be routed to a central reception team, who can then transfer callers to the right site.
Do we have to move all sites at once?
No. Sites can be moved in stages or together, depending on what suits your business.