The BT Ambassador is a telephone

Telephone

The telephone , colloquially referred to as a phone, is a telecommunications device that transmits and receives sounds, usually the human voice. Telephones are a point-to-point communication system whose most basic function is to allow two people separated by large distances to talk to each other...

 private branch exchange switchboard. Manufactured for BT by GEC, it was discontinued in 1991. There was a larger version called Senator. Both systems used proprietary phones, allowed direct access to outside lines (with lamp indication), had an intercom facility and allowed basic call diversion. Apart from this, there were few features, and these systems are now obsolete. Ambassador systems handled 1 line & 3 extensions or 2 lines and 4 extensions, while the Senator could handle 5 lines and 10 extensions, depending on the cards in the control unit. Used Ambassador and Senator equipment is available on the second hand market in the United Kingdom

United Kingdom

The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

. These days they could provide intercoms facilities for private homes but do not have much use in a modern office

Office

An office is generally a room or other area in which people work, but may also denote a position within an organization with specific duties attached to it ; the latter is in fact an earlier usage, office as place originally referring to the location of one's duty. When used as an adjective, the...

, due to lack of features and interoperability.