Telephone headset amplifier and method of operation
Telephone instrument and method for altering audible characteris
Telephone instrument and method for altering audible characteris
Telephone interface for simultaneous audio presentation at separ
Telephone line current modulator
Telephone line seizure circuit
Telephone privacy device
Telephone set comprising a line voltage stabilizer having a DC s
Telephone set having a volatile memory
Telephone set usable as an acoustic coupler
Telephone set with background noise suppression function
Telephone set with circuit for suppression of howling and echo
Telephone subscriber system incorporating a drive interface for
Telephone system with automatic volume control
Telephone terminal having multiple handsets
Terminal apparatus having a function for preventing unnecessary
Terminal apparatus with a handset using a four pin connector
Universal apparatus and method for interfacing signals with...
User configurable telephone with alarm feature
Vocal frequency suppression apparatus and method