Copper Is Going. Not All of It Needs Replacing.

Desk phones were migrated years ago. What is left on copper is the estate nobody has an inventory of, in places nobody visits:

• Lift emergency phones and refuge points — often the only line in the building anyone is legally obliged to keep working
• Intruder and fire alarm signalling — quietly dialling out over a line that is about to be withdrawn
• Door entry, gate intercoms and barrier phones — usually installed by someone who has long since left
• Fax lines, franking machines and lone-worker phones — low usage, full standing charge
• Outbuildings, plant rooms and portacabins — where running new cable costs more than the line ever did

These lines carry almost no traffic and cost the same as the ones that do. They are also the ones a migration project discovers last, because they belong to facilities rather than to IT.

An analogue estate divides in two, and the halves need opposite treatment.

Lines used by people mostly do not need replacing at all. A business line delivered by eSIM to the phone somebody already carries is an extension of your existing platform, so the number, the routing and the call record all survive the copper going. No handset, no new cabling, no site visit.

Lines used by devices do need replacing, and this is where the cheap answer is the wrong one. An IoT SIM is inexpensive but carries voice as best-effort data, which is not what you want on a lift phone. A VoLTE SIM gives proper call quality but is usually expensive and sits outside your phone system entirely, so nothing you do to monitor or record calls applies to it.

Tango Extend gives VoLTE call quality at close to IoT pricing, and routes the call through your own platform — Microsoft Teams Phone, Cisco Webex Calling, BroadWorks, NetSapiens, Zoom Phone and others. A call from an emergency call box behaves like any other call on your system: it can be recorded, routed, escalated and reported on.

One thing to plan rather than assume. Emergency calling from replaced device lines needs to be designed deliberately — it is not automatic, and it is the first thing to settle for lifts and refuge points.