H04M1/00—Substation equipment, e.g. for use by subscribers
H04M1/26—Devices for calling a subscriber
H04M1/515—Devices for calling a subscriber by generating or selecting signals other than trains of pulses of similar shape, or signals other than currents of one or more different frequencies, e.g. generation of DC signals of alternating polarity, coded pulses or impedance dialling
Poste téléphonique comportant un préamplificateur à courant porteur, un interrupteur de coupure de micro et un dispositif de signalisation de cette coupure