The UK to axe analogue landlines for digital-only telecom system

01-09-2021 |   |  By Robin Mitchell

Recently, BT announced that all landlines in the UK would switch over to a digital system in 2025. What will the switchover do, how will it help with infrastructure, and how will it affect those with poor connections?

What is the landline switch over?

Telephones are a century-old technology that has enabled instant conversations across vast distances, yet their operating is remarkably simple. A single twisted pair is used to carry both receiving and transmission signals that utilise clever circuitry to keep the two from interfering. Each household has its twisted pair of cables, which all meet up at nearby telephone lines, and these large bundles of cables then arrive at an exchange that automatically routes calls.

While this operation is simple, it is entirely based on analogue technology, which can cause challenges when many phone calls have to be sent down a single line. Telephone calls have a narrow bandwidth, making them more muffled but allowing more calls to be multiplexed down the same transmission line. Multiplexing is an attempt to try and improve bandwidth.

This challenge is made worse when considering that many receive internet through their landline in the form of broadband. Even to this day, anyone who uses their landline for the internet must use an ASDL splitter that separates analogue telephone conversations from broadband services.

Recently, an announcement outlined how old analogue methods for transmitting telephone conversations will be replaced with a digital system. This switchover is not due to occur until 2025, but telephone conversations will require an internet connection when it does.

How will “all-digital” infrastructure help?

One of the most significant advantages of an all-digital system is that digital data is far easier to compress and transmit than analogue audio signals. Compression means that more conversations can be transmitted over a single line, and the quality of these calls can be significantly improved. As such, the introduction of the digital telephone should see muffled voices disappear and call quality approach that of video calls.

Another significant advantage to all-digital systems is that they can be entirely controlled with digital equipment. While modern phone exchanges will use digital systems to convert incoming analogue signals into digital ones, it puts pressure on the telecom service side to integrate digital signal processors. If an entirely digital system is used, the customer’s device already converted audio signals into digital signals. Digital signal processors mean a message can be sent and then re-routed with no need for additional stages.

However, the biggest advantage by far is that a digital system could utilise internet technologies. This means that telecom services such as BT can spend more money on improving internet connections while dedicating all exchanges to purely internet services.

How will this switch over affect those with poor connections?

One of the biggest concerns with this plan is its effect on the older generation and those who live in rural counties.

It is no surprise that elder generations generally lack technological integration. This can be for several reasons, including resistance to change, inability to learn new systems, and the rapid rate of technological change is too fast. The replacement of analogue systems with digital services does not increase the complexity in use but can create challenges using newer devices. Unless new digital phones are designed with an old-fashioned feel, many could face challenges when using new digital equipment.

Despite the current state of modern technology, it is estimated that 6% of homes in the UK do not have an internet connection. Worse, many of these places also lack quality mobile reception meaning that an internet connection through cellular networks is out of the question. This means that an entirely digital system would leave out homes without an internet connection.

While there are concerns with the analogue to digital switchover, it has to be done to improve telecommunications and increase data rates. The replacement of any technology will always be left behind, and while engineers do their best to support such individuals, technology must continue to progress.


By Robin Mitchell

Robin Mitchell is an electronic engineer who has been involved in electronics since the age of 13. After completing a BEng at the University of Warwick, Robin moved into the field of online content creation developing articles, news pieces, and projects aimed at professionals and makers alike. Currently, Robin runs a small electronics business, MitchElectronics, which produces educational kits and resources.

Related articles