EP 1142292 A1 20011010 - TELEPHONE LINE INTERFACE CIRCUIT WITHOUT HOOKSWITCH
Title (en)
TELEPHONE LINE INTERFACE CIRCUIT WITHOUT HOOKSWITCH
Title (de)
FERNSPRECHLEITUNGSSCHNITTSTELLENSCHALTUNG OHNE GABELUMSCHALTER
Title (fr)
CIRCUIT D'INTERFACE DE LIGNE TELEPHONIQUE SANS CROCHET COMMUTATEUR
Publication
Application
Priority
- US 9930098 W 19991216
- US 21270798 A 19981216
Abstract (en)
[origin: WO0036813A1] A novel electronic inductor circuit is used to establish a DC current drawn from the telephone line needed for indicating to a central office (or PBX) that a telephone device (i.e. a modem) has seized the line. The electronic inductor's transistor is used to perform the functions of a hookswitch, thereby avoiding the introduction of unwanted impedance in the AC signal path of the device. In order to go on-hook, the electronic inductor's transistor (upon receiving a control signal) stops drawing current from the central office loop indicating that it is now in the on-hook state. Unlike a switch, the present invention operates by starting and stopping the DC current while the entire circuit remains connected to the line at all times. The line is "seized" by providing a control voltage to turn on the electronic inductor and thereby initialize line current to flow through its transistor - thus achieving the "off-hook" state.
IPC 1-7
IPC 8 full level
H04M 1/82 (2006.01); H04M 11/06 (2006.01)
CPC (source: EP)
H04M 1/82 (2013.01); H04M 11/06 (2013.01)
Citation (search report)
See references of WO 0036813A1
Designated contracting state (EPC)
AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE
DOCDB simple family (publication)
WO 0036813 A1 20000622; CN 1330830 A 20020109; EP 1142292 A1 20011010; TW 456137 B 20010921
DOCDB simple family (application)
US 9930098 W 19991216; CN 99814467 A 19991216; EP 99966377 A 19991216; TW 88122093 A 19991218