A detecting circuit for detecting the presence of a headset connected to a telephone, and a method for detecting a headset connected to a telephone
IES20020615A2
A private branch exchange, and a method for selectively communicating the central processing unit with respective modules in the private branch exchange
GB0022214D0
A circuit for developing an ac ringing voltage from a dc voltage supply
IE20000106A1
A circuit for developing an AC ringing voltage from a DC voltage supply
IES20000107A2
A circuit for developing an AC ringing voltage from a DC voltage supply
IES970665A2
A synchronising circuit for a PBX for synchronising a PCM clock signal with basic rate ISDN network signals
IE970664A1
A synchronising circuit for a PBX for synchronising a PCM clock signal with basic rate ISDN network signals
IE970331A1
A line voltage monitoring circuit
IES78910B2
A line voltage monitoring circuit
IE960235A1
A ringing voltage trigger circuit
IES65389B2
A communicating circuit
IES950210A2
A ringing voltage trigger circuit
IE903790A1
A digital signal send circuit
IE903789A1
A speech and ringer volume attenuation control circuit for a telephone
