Special offer — Free number port + free setup Claim it

Switch-off

PSTN Switch Off for Multi-Site and Multi-Location Businesses

Migrating one office off an analogue line is a small job. Migrating eight sites that were set up at different times by different people is a different exercise. The complexity is rarely in the phones — it's in what varies between locations.

Blog · Published 31 August 2026 · Last updated 31 August 2026

Why multiple sites are harder than one

Sites accumulate their own history. One location may be on ISDN into an old PBX, another on a couple of analogue lines, a third on something a previous manager arranged and nobody documented.

  • Different legacy equipment and handset types per site
  • Different broadband providers, speeds and contract end dates
  • Different connected systems: alarms, EPOS, door entry, lift lines
  • Different opening hours and call routing expectations
  • Numbers held with more than one provider

A plan built from head office assumptions usually breaks at the third site. The variation is the project.

Start with a site-by-site audit

For each location, record the lines in use, the numbers on them, what's physically plugged in, the broadband service and who supports it. Ask the person who actually works there, not just the account paperwork — the paperwork is often out of date.

Two things usually fall out of this immediately: lines nobody can account for that can be ceased, and a site whose broadband needs upgrading before it can carry voice properly. Both are better known now than mid-migration.

Phase it — don't attempt one simultaneous cutover

There is no requirement to move every location on the same day, and good reason not to. Moving one site first gives you a tested pattern: how the routing should be built, how long the port takes, what the local checks need to cover.

Sequence the rest by risk. Simplest site first to prove the process, highest call volume site last with the most preparation. Sites can share the same system while being migrated on different dates, so internal calling still works across the estate.

Check connected equipment at every site

Alarms and payment terminals are the two items most often missed, and they vary by location even within the same business. A panel that supports IP signalling at one site may be an older model at another.

Our guides on alarm systems after the switch-off and card machines and EPOS cover what to ask your installer and provider. Run those questions per site rather than once centrally.

How we support multi-site migrations

We build the audit with you, agree the site order, and set up the call routing for the whole estate up front so numbers can be ported into it in stages. Each site gets its own cutover date and a check afterwards before the next one starts.

Have a look at our business phone systems page for how the system works across locations, or send us your site list and we'll come back with a sequence and a timeline.

Want this set up for you?

Plans start at £19 per user per month with UK calls included. See pricing or get a quote.

Related pages

Business phone systems

A full cloud system for a growing team.

More about business phone systems

PSTN replacement

What the switch-off means for your lines.

More about pstn replacement

Talk to us

Get a quote or book a call with a UK specialist.

More about talk to us

Related guides

Will My Alarm System Still Work After the PSTN Switch Off?

Alarms, telecare and other equipment wired into a phone line are affected by the PSTN switch-off. Here's the difference between single-path and dual-path signalling, and what to check.

Read: Will My Alarm System Still Work After the PSTN Switch Off?

PSTN Switch Off: What It Means for Card Machines and EPOS Systems

Card terminals and EPOS systems that authorise over a phone line are affected by the PSTN switch-off. What to check with your provider and how to plan it alongside your phones.

Read: PSTN Switch Off: What It Means for Card Machines and EPOS Systems

When Is the ISDN Switch Off? What UK Businesses Need to Know

The ISDN switch off date is 31 January 2027, the same as the PSTN. What ISDN2 and ISDN30 withdrawal means, why migration takes longer, and what to audit first.

Read: When Is the ISDN Switch Off? What UK Businesses Need to Know

Ready to switch to a smarter phone system?

Special offer: free number port and free setup — worth £174. Talk to a UK specialist today, no pressure and no jargon.