Telecom test equipment is a special type of telephone used by technicians when installing and testing local loop telephone system. This system is a circuit that connects from a customer's premises to the telecommunications service provider's network.
A telephone headset typically connects via a pair of test leads, and will have some combination of crocodile clips, and a piercing spike for the insulated wires. They can be connected wherever there are wires accessible. This could be inside or behind the housing of a modular connector (electrical connector) or at a network interface (point of interconnection between a computer and a private or public network). As a specialist device, telecom test equipment is capable of monitoring calls, as well as fulfilling standard telecom functions like answering incoming calls and making outgoing calls.
Typical components of telecom test equipment include an earpiece, a mouthpiece, a dialling interface and a variety of different test leads for connecting to the telephone circuit. The majority of handsets are made to be used with telephone lines and have limited or no capability with digital circuits.