Analogue PSTN terminal support interface|Telephone equipment, Electric sockets, Signal level, Telephone networks, Telephony, Electric connectors, Electrical testing, Performance testing, Communication equipment, Classification systems, Approval testing, Circuits, Telecommunication systems, Testing conditions, Accuracy, Analogue circuits, Direct current, Signal strength, Performance, Electrical impedance, Interfaces (data processing), Public switched telephone network, Noise (spurious signals), Radiocommunication, Electric terminals, Interfaces, Test equipment, Analogue signals, Signal transmission, Electronic telephone switching systems Network interconnection