Telephone

The telephone (or phone) was a technology developed by Humans on Earth during their civilization's industrial era. Utilizing electromagnetic encoding of sounds and voices transmitted over wires, and eventually with radio waves, the telephone became Earth's first major networked communications system. Similar developments existed on many worlds, such as Miri's homeworld, Ekos, Magna Roma, and others.

Configurations and history
The simplest telephone was a speaker, and receiver, for projecting voice and picking up incoming sounds, repectively. Wires connected from the phone to a network transmitted the sounds. The earliest telephones required the user to know a code or number that was the target of their call, and ask an operator to connect the call. This process became automated as technology progressed, and a caller could enter the desired connection into a control mechanism, a process known as dialing

Phone numbers
As telephones became more and more common on Earth, the codes for contacting specific locations became more detailed. Most people had a phone number, which was a code that sent calls to their phone. Directories of persons listed with their numbers were common, in order to make it easy to find a person whose number wasn't immediately known.

Companies competing to provide phone service often advertised the quality of their service and directories, despite all service provided being relatively similar. Some phone companies paid for outlandish billboards, such as one company that painted an advertisement directly on the side of a building that contained a residence in San Fransisco in the 1980s. 

In social situations, Humans often regarded the sharing of a phone number as an invitation for continued social contact. When Gillian Taylor arrived in the 23rd century, James T. Kirk attempted to speak in her 20th century language by saying that he "didn't even have her phone number". 

Telephone booth
A telephone booth or call box was an enclosure which contained a phone that was open to the public, usually paid for with money deposited into the mechanism of the phone. In emergency use, phone calls were free. For example, London had many public call boxes to summon police, firefighters, or medical assistance. Directories were also sometimes available at phone booths.

Time travel
A London police call box was sometimes used as a template in a camouflage system on a time travelling TARDIS.

In an alternate reality, phone booths modified for time travel, at least one of which was a TARDIS, were deposited on Earth at some point prior to the 23rd century. In this reality, Emperor Vandar tracked these phone booths when they arrived in his space-time, and captured their occupants, and took the booths to his trophy room. These time travel enclosures were present when he captured and entertained Captain James T. Kirk and landing party, who had been captured along with a number of Legionnaires from yet another reality.