Jack is a connecting device usually in the wall into which a plug can be plugged to from a connection such as the telephone jack
Jumper may refer to the following things: (1) a wire that connects equipment and cable on a distributing frame in a telephone system. (2) when called as a jumper wire, it is a wire or connector used to establish a circuit for testing. (3) a metal bridge that connects parts of an electrical circuit that can be used to configure expansion boards. (4) an electrical switch consisting of a number of pins and a connector that can be attached to the pins in a variety of ways.
A junction is a point in the telecommunications network that comprises a switching office or facility cross-connect and/or ADM hardware, a point of connectivity where multiple fiber links come together, and/or a source or destination for a wavelength path.
Junctor refers to a connection or circuit, within a switching system, between inlets and outlets of the same or different switching networks. An interoffice trunk is an example of junctor.
Junctor Trunk Group is a special-purpose trunk group providing a particular feature such as coin control, billing supervision, etc.
Jurisdiction refers to, in telecommunication, a geographic area presided over by the same regulatory body, within the boundary of a single state or an area in which a common carrier is authorized to provide telephony service.
Key Pulsing is a method of signaling by depressing keys on a line otherwise arranged for rotary pulse dialing.
Key Station Line refers to the circuit which extends from the key set to the key system common equipment.
Key System refers to a group of associated key sets and common equipment located on a customer's premises and connected to provide various features accessible to a key set.
Key Telephone Set refers to a telephone instrument with keys or buttons which are used to select a specific line from several possible incoming lines. Those buttons usually have lamps and can provide features such as call holding, line status, signaling, conferencing and intercom.
Key Telephone System refers to a multi-line telephone system that is typically adopted and installed in small business or office environments. Key telephone system is good for its expandability and the individual line selection buttons for each connected phone line.