The telephone or phone (Greek: tele = far away and phone = voice) is a telecommunications device to transmits and receives sound (most commonly voice and speech) through great distances. Most telephones function by means of electric signals over a complex public switched telephone network of equipment which allows almost any phone user to speak to almost any other.
Until relatively recently the word telephone could generally be assumed to refer to a landline phone. Now, cordless telephones and cell phones have become sufficiently common that no such presumption can be made. There are four principal means by which telephone signals are transmitted: throughout a traditional landline which uses physical dedicated wire connections; wireless or Radiotelephony, which transmits messages using either analog or digital radio signals; satellite telephones which bounce signals off of telecommunications satelites; and voice over internet protocol (VOIP) telephones, which use broadband internet cables.
The electric telephone is recognized to various inventors. The actual history is a subject of complex dispute. Among others Antonio Meucci, Philip Reis, and Alexander Graham Bell are all credited with inventing.