Landline

A landline, also known as a fixed line, is a telephone service provided to a subscriber through physical connections. These connections use cables or wires, such as metal conductors or optical fiber. This service is distinct from wireless mobile services that are now found everywhere. One unique feature of a landline is that it allows multiple telephones to operate at the same time using a single phone number. People often refer to this traditional system as plain old telephone service, or POTS.

The mechanism of a landline relies on a complex network called the outside plant. This network begins at a central office, which is sometimes called a wirecenter. From this central point, analogue copper wires travel through various tiers of cabling. These cables pass through different distribution points within an exchange area. Eventually, a single pair of copper wires or an optical fiber reaches a subscriber's home or office. This specific connection point is known as the network interface, or NID. From the NID, customer premises wiring extends to the actual telephones inside the building.

Landline technology can support various types of services and connections. Some lines carry high-speed internet through a digital subscriber line, or DSL. This system links the user back to a digital subscriber line access multiplexer, known as a DSLAM, located in the central office. Other types of connections include T-1, T-3, or an Integrated Services Digital Network, or ISDN. While many modern phones are cordless, some landline sets use a hard-wired handset. Interestingly, wired handset landline telephones do not require mains electricity to function.

Historically, landline networks were the primary way the world communicated. In 2003, the CIA World Factbook reported approximately 1.263 billion main telephone lines worldwide. China led the world with more than 350 million lines. The United States held the second position with 268 million lines. The United Kingdom had 23.7 million residential fixed home telephones at that time.

However, the early 21st century saw a decline in landline installations. This change happened because mobile network technology advanced and copper wire networking became obsolete.

Global usage statistics show a massive shift toward mobile technology. In Africa, mobile phone growth has outpaced landline growth. Between 1998 and 2008, Africa added only 2.4 million landlines. In contrast, mobile use rose from fewer than 2 in 100 people to 33 out of 100 between 2000 and 2008.

In the United States, the shift is also clear. In 2004, only 45.9 percent of people aged 12 to 17 owned cell phones. By 2013, 91 percent of adults in the U.S. owned a mobile phone.

Modern alternatives like Voice over IP, or VoIP, are changing how we use phone numbers. VoIP services allow numbers to be used without being tied to a physical location. This is possible through VoIP porting, which lets a landline number move to a different service. VoIP can be used on many devices, including smartphones, wherever an internet connection is available. This flexibility helps people with remote, mobile, and home working. In the United Kingdom, the analogue copper network is scheduled to be terminated by 2027. Other countries, including France, Germany, and Japan, are also in the process of replacing their traditional networks.

Different countries show very different levels of landline use today. In 2022, 82.9 percent of German households had at least one landline phone. In contrast, 73 percent of U.S. households used only a cell phone in 2022. Australia has also seen a decline, with reports in 2021 showing only 14.5 percent of households used a landline at home. Some nations have already moved past the old systems entirely. Estonia and the Netherlands have retired the legacy parts of the public switched telephone network, or PSTN.