Patent ID: 6853725
Filing Date: 2005-02-08
Classification: H04M,H04Q

Abstract:
1. A channel unit in a digital loop carrier, the channel unit being coupled to at least one telephone via a subscriber line, the at least one telephony device being operable to generate tones, the channel unit comprising: a tone detector coupled to said subscriber line, said tone detector being operable to detect tones transmitted via said subscriber line to produce an output corresponding to an off-hook control signal; a processing device coupled to said tone detector and programmable to receive said output of said tone detector, to evaluate said output to determine if said tones corresponding thereto represent said off-hook control signal, said off-hook control signal using at least one of a preselected order, a preselected number and preselected ones of said tones, said processing device being operable to maintain said subscriber line off-hook for a selected period of time if said output indicates said off-hook control signal, and maintain said telephony device off-hook and on-hook in accordance with when a subscriber line requests and terminates, respectively, a connection via said subscriber line using said telephony device, if said programmable device determines that said tone is not said off-hook sequence tone.