It’s the end for the UK analogue telephone network

BT Openreach maintains the cables and infrastructure that connect homes and business in the UK to the national telephone and broadband network. They are aiming to end the life of the traditional analogue phone network (or PSTN) by December 2025.

Background information

Over the last 40 years the UK Public Switch Telephone Network (PSTN), more commonly known as “the landline network”, has undergone several fundamental changes. Readers of similar age to myself will remember the disappearance of rotary dial phones in the 1980s to be replaced by the (at the time) thoroughly modern push button designs. However, now, for the first-time changes are happening that are impacting the lift industry, as telephone lines and autodiallers become increasingly incompatible.

What’s happening?

Internet/data services have overtaken voice services over the past 25 years. This has left the original copper cable infrastructure in the UK struggling to keep up with our demands for ever faster data. To better serve our needs now and for the future, copper cable is being replaced with fibre optic as the standard UK telephone line cable.

Whilst the deployment of fibre lines began in the 1990s it is in the last 5 years that the rate of fibre installs has really stepped up.

Until now this has not affected the lift industry, but in 2020 Openreach (the organisation responsible for the UK PSTN infrastructure) began to withdraw support for analogue signalling/services across the UK landline network regardless of whether the line was copper or fibre.

Why does this affect the lift industry?

Older autodialler designs rely on both an analogue dial tone and dual tone multi frequency (DTMF) signalling to operate.

As support for these analogue services is being withdrawn, many autodiallers with landline connects will fail to dial out if a passenger tries to place an alarm call (no dial tone) and will be unable to place their 72-hour test calls (no DTMF).

In addition to the above changes, the 48V line voltage is also being withdrawn. Autodiallers which draw their power from the telephone line (line powered autodiallers) will cease to function.

The removal of line voltage also presents a risk when using landlines for emergency communication. Fibre lines require their own mains power connection to function. Therefore, they will also require a separate battery backup to continue to function in the event of a mains power failure. Provisioning and maintenance of these battery backups will fall on the building/telephone line owner. That means there is a very real risk of a mains power failure causing a lift trapping and the telephone line also failing!

What can I do to ensure my autodialler continues to operate?

Existing analogue autodiallers, such as the Memcom unit, should be moved from their current landline connection to a GSM gateway, such as the Digital Communication Platform (DCP). This allows the autodialler to continue to communicate – as well as still supporting the required analogue signalling. The cost of a SIM card is significantly lower than a commercial landline rental. This allows for a return on investment, as the savings in the communication costs will offset the cost of the DCP hardware and installation.

We recommend that line powered units be replaced with a DCP/DAU system for a full digital upgrade. This is because the power supplies and battery backups which are required to maintain EN81-28 compliant operation for these devices are liable to be expensive and relatively complex pieces of hardware (consult the original equipment manufacturer for specific recommendations).