Automatic echo cancellation for an integrated services digital network interface

Claim 1

A method of processing telecommunications signals on a digital communication link having a plurality of communication channels, comprising the steps of: detecting a request message on a first channel of the link to establish a requested call to be conducted on a second channel of the link; determining on the basis of the information in the request message, and prior to establishment of the requested call, whether the requested call is to communicate digital information of a predetermined type designated for an audio signal processing function to be applied to signals communicated during the call; and applying said audio signal processing function to signals communicated during the call; wherein said detecting step comprises the steps of: monitoring transmissions conducted on the first channel of said communication link; identifying, within said first channel, the request message including said request to establish a call on the second channel of the communication link; and wherein said determining step comprises: obtaining, from said request message, a call reference value assigned to the requested call, an information content value identifying the type of information contained in said requested call, and a channel identification value identifying said second channel; comparing the information content value with a selected information content value for which said signal processing friction is to be applied; and storing said call reference value, said channel identification value, and a flag indicating the outcome of said comparing step.

Claim 2

A method of processing telecommunications signals on a digital communication link having a plurality of communication channels, comprising the steps of: detecting a request message on a first channel of the link to establish a requested call to be conducted on a second channel of the link; determining on the basis of the information in the request message, and prior to establishment of the requested call, whether the requested call is to communicate digital information of a predetermined type designated for an audio signal processing function to be applied to signals communicated during the call; and applying said audio signal processing function to signals communicated during the call; wherein said detecting step comprises the steps of: monitoring transmissions conducted on the first channel of said communication link; identifying, within said first channel, the request message including said request to establish a call on the second channel of the communication link; and wherein said determining step comprises: obtaining, from said request message, a call reference value assigned to the requested call, an information content value identifying the type of information contained in said requested call, and a channel identification value identifying said second channel; comparing the information content value with a selected information content value for which said signal processing friction is to be applied; and storing said call reference value, said channel identification value, and a flag indicating the outcome of said comparing step.

Claim 10

An apparatus for selectively providing audio signal processing upon telecommunication signals communicated between a local communication network and an integrated services digital network, comprising: a send input for receiving a first multi-channel signal from a local communication network; a receive input for receiving a second multi-channel signal from the integrated services digital network; a receive output, connected with said receive input, for transmitting said second multi-channel signal to the local communication network; an audio signal processor, connected with said receive input and with said send input, for performing audio signal processing within a channel of the first multi-channel signal, and thereby producing a third multi-channel signal; a send output for transmitting said third multi-channel signal to the integrated services digital network; and selection means for (i) monitoring a first channel of at least one of said first and second multi-channel signals, (ii) detecting a call control message within said first channel identifying the type of signal within a second channel of said at least one of said first and second multi-channel signals, (iii) determining whether said identified type of signal is of a predetermined type designated for audio signal processing, and (iv) instructing said audio signal processor to select said second channel for audio signal processing.

Claim 11

An apparatus for selectively providing audio signal processing upon telecommunication signals communicated between a local communication network and an integrated services digital network, comprising: a send input for receiving a first multi-channel signal from a local communication network; a receive input for receiving a second multi-channel signal from the integrated services digital network; a receive output, connected with said receive input, for transmitting said second multi-channel signal to the local communication network; an audio signal processor, connected with said receive input and with said send input, for performing audio signal processing within a channel of the first multi-channel signal, and thereby producing a third multi-channel signal; a send output for transmitting said third multi-channel signal to the integrated services digital network; and selection means for (i) monitoring a first channel of at least one of said first and second multi-channel signals, (ii) detecting a call control message within said first channel identifying the type of signal within a second channel of said at least one of said first and second multi-channel signals, (iii) determining whether said identified type of signal is of a predetermined type designated for audio signal processing, and (iv) instructing said audio signal processor to select said second channel for audio signal processing.