Patent ID: 7180869

Claim:
A method for controlling echoes within a telecommunication switching system having a plurality of local exchange carriers and a plurality of local telecommunication switches where each of the plurality of local exchange carriers is connected to a plurality of telephone sets attached to a plurality of local telephone switching offices of each of the plurality of local exchange carriers and each of the plurality of local telecommunication switches is connected to a plurality of telephone sets, comprising the steps of: receiving by one of the plurality of local telecommunication switches a call setup message from one of a first plurality of telephone sets connected to one of a first plurality of local exchange carriers with a first trunk circuit interconnecting the one of the plurality of local telecommunication switches with the one of the first plurality of local exchange carriers; determining by the one of the plurality of local telecommunication switches that the call setup message designates one of a second plurality of telephone sets connected to one of a second plurality of local exchange carriers as a destination of the call setup message; determining by the one of the plurality of local telecommunication switches in response to the call setup message that a first one of a first plurality of local telephone switching offices of the one of the first plurality of local exchange carriers to which the one of the first plurality of telephone sets is connected requires echo cancellation operations; providing by the one of the plurality of local telecommunication switches in response to the determination that echo cancellation operations are required for the first one of the first plurality of local telephone switching offices echo cancellation operations for a first call path from the one of the plurality of local telecommunication switches to the first one of the first plurality of the local telephone switching offices of the first one of the plurality of local exchange carries; and adjusting the echo cancellation capabilities of the first trunk circuit with respect to an echo tail length upon the first call path being established.