Beyond the Desk Phone: A 2026 Audit of the Analogue Lines VoIP Rollouts Leave Behind

The migration that stops at the handset

A telephone migration usually starts with a sensible question: how many handsets do we have, and what replaces them? The answer is a count, a quotation and a cutover date. What that process rarely captures is the second estate, the lines that carry no conversation at all. These are the pairs running a lift alarm in a stairwell, a fire panel in a lobby, an intruder system in a stockroom, a card terminal at a trade counter, a fax in accounts, or the modest broadband circuit a till depends on.

The retirement of the public switched telephone network has been discussed for years, and the timetable has shifted more than once. Openreach has been moving exchanges in waves, stop-sell has already been applied across much of the country, and full withdrawal is expected during 2027. The exact date matters less than the direction of travel. Every device currently sitting on an analogue line needs somewhere else to live, and firms that treat the exercise as a handset swap tend to meet the rest of the estate in the final week.

Start with the bill, not with the desk

An inventory built from the desk tells you what people use. An inventory built from the bill tells you what you pay for. Begin with twelve months of telecoms invoices and list every recurring charge, including line rental, broadband, alarm circuits, redcare-style signalling, ISDN channels and any single-line items that no one recognises. Match each charge to a physical location. Anything that cannot be matched is either a genuine hidden line or a billing error, and both are worth finding.

A practical sweep covers:

• the comms room and any secondary cabinets, including disused patch panels;
• lift motor rooms and the alarm intercom in each car;
• fire and intruder panels, including remote signalling paths;
• tills, payment terminals and any analogue backup path for card payments;
• fax machines and franking or mailing equipment in finance;
• out-of-hours and courtesy lines, often shared across sites;
• broadband circuits delivered over a phone line rather than dedicated Ethernet.

Photograph every device you find, note the number on the socket, and record who maintains it. That record becomes the backbone of the whole migration.

Classify before you commit

Not every line deserves the same treatment. Sort what you have found into three rough bands. The first is life safety: lift alarms, fire signalling and telecare devices, where failure could injure someone or breach a statutory duty. The second is commercial: card terminals, alarm systems protecting stock, and anything whose outage stops trading. The third is convenience: faxes, legacy modems and the line nobody can quite account for.

Life-safety devices deserve their own track. Many older lift and fire communicators were designed around a copper pair and a simple tone-based protocol, and they behave unpredictably when pushed through a compressed voice codec. The standards governing alarm transmission assume more than one signalling path and a defined response if the first fails. That is a conversation for the maintainer, not for the IT team alone.

Talk to maintainers before choosing a platform

Lift engineers, fire alarm providers and security installers will each have a preferred approach, usually a dual-path communicator using a wired connection plus a mobile data path. Some will insist on a dedicated line; others will accept a managed analogue terminal adaptor. Raising this early gives you three things: a compatibility answer, a price, and a realistic lead time for parts and site visits.

Ask each maintainer directly which communicators on your site are end-of-life, what they recommend as a replacement, and what they need from the network. Get the answer in writing and attach it to the migration plan. If a supplier says the existing device will work over the new service, ask them to confirm that in writing as well, and to state who carries the risk if it does not.

Test the failure modes, not the happy path

A demonstration call proves very little. What matters is behaviour when something else has already gone wrong. Build a test plan that covers the following:

• a mains power interruption at the premises, checking that alarms still signal on their backup path;
• a broadband outage, checking whether the voice service fails over to a mobile or secondary connection as designed;
• a busy period, checking call quality and whether alarm calls compete for bandwidth with card payments;
• a silent line, checking that the alarm panel detects the loss of the path rather than assuming success;
• a full alarm activation, witnessed by the receiving centre and logged by them.

Record each result with a date and a name. If a test cannot be performed, write down why. An untested assumption is the most common cause of a post-migration incident.

Numbers, contracts and the awkward leftovers

Number portability needs a named owner. Gather the numbers in scope, confirm which are published, which appear on vehicles and stationery, and which sit on contracts with notice periods that do not line up with the cutover date. Porting is usually manageable but rarely instant, and a missed notice period can cost a month of double running.

Some lines will be genuinely difficult to replace. A fax used daily by a supplier that has no portal, an analogue modem on a legacy till, a door entry system in a shared building where the freeholder controls the infrastructure. Do not force these into the new platform for the sake of tidiness. A small number of retained analogue or managed solutions may be the cheaper and safer answer, provided someone is accountable for reviewing them each year.

Keep the map after the cutover

The value of the audit is not just the migration. It is the register that survives it. Keep the device list, the maintainer contacts, the test results and the contract dates in one place that the next IT manager can find. Add new lines and devices to it when they are installed, not afterwards.

The PSTN withdrawal rewards organisations that started early with an accurate picture of what they own. It punishes those who assumed the only thing on the line was a telephone.