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