Patent ID: 7184544

Claim:
A method for detecting presence of service on a subscriber line in a communications network, comprising the steps of: performing a first voltage detection on a subscriber line (S 20 ); activating a subscriber line interface circuit (SLIC) if no other service is detected on the subscriber line (S 30 ), the SLIC providing an interface between the subscriber line and a service provider; and performing a second voltage detection on the subscriber line after a usage-dependent time has elapsed (S 60 ); and using a timer and heuristics to determine whether the usage-dependent time has elapsed, the heuristics considering one of whether the subscriber line is off hook, whether it is a time of low call traffic, whether the SLIC recently started up, whether the SLIC is operating from battery power or has recently switched from battery power to line power and when a last call on the subscriber line is completed.