Abstract: A communication system provides a clear channel link for transport of encrypted payload across a network of the communication system. When a source access network receives, via an air interface, a frame that is formatted pursuant to an air interface protocol and that comprises encrypted payload, the source access network demultiplexes the frame to separate the encrypted payload and assembles an Intersystem Link Protocol (ISLP) frame that comprises the encrypted payload. The source access network adds a link layer header to the ISLP frame that identifies one or more of frame type information and a sequence value associated with the frame and conveys the ISLP frame and added header across the network, for example, to a destination access network. Based on the added header, the source and destination access networks are able to perform clear channel synchronization.

Abstract: Upon receiving (101) a vocoded voice frame and detecting (102) that the received vocoded voice frame comprises an erased frame, one automatically replaces (103) the erased frame with a valid frame having at least one error condition. In a preferred approach this error condition is one that is known to cause a receiving target platform to invoke a corresponding erasure process with respect to the valid frame when received.

Abstract: A method and apparatus for effecting multi-party teleconferencing that avoids the need for tandem vocoding of packet based information from conference call participants. In particular, the teleconferencing bridge infrastructure utilizes packet tagging of encoded packets with a tag as well as adaptive scheduling of bandwidth to transmit packet based information to the end user call participants. Decoding is accomplished at each end user based on information included within the tag such that an appropriate decoding algorithm is selected for the packet-based audio information thereby avoiding tandem vocoding.

Abstract: A method and apparatus that performs specific automatic gain control in an echo canceller (16). The disclosed method and apparatus utilize a low complexity algorithm that performs automatic gain control to achieve greater speed of convergence of the echo canceller (16) and an increased ability to distinguish between near-end speech and echo through the use of specific automatic gain control. A double talk threshold of the echo canceller is adjusted by using, in part, computed gains of inbound and outbound signals internally within the echo canceller in order to adjust the echo canceller double talk threshold.

Abstract: An apparatus (200) checks voice quality when in a vocoder bypass mode. If the voice quality level is beyond an acceptable range, the apparatus (200) ends the vocoder bypass mode and returns to tandem vocoding. For example, a vocoder bypass controller (206) includes a speech quality detector (225) that determines the speech quality level of speech information based on at least one of detected volume level, echo level and noise level of the speech information. The vocoder bypass controller (206) with the speech quality detector (225) outputs a speech quality-based vocoder bypass control signal (236) to selectively activate or deactivate a vocoder bypass operation in response to the speech quality-based vocoder bypass control signal (236). In another embodiment, a network element for communicating speech packets includes an incoming decoder (512) and a speech quality detector (514) operative to determine the speech quality level of incoming speech packets.

Abstract: A method and apparatus for effecting multi-party teleconferencing that avoids the need for tandem vocoding of packet based information from conference call participants. In particular, the teleconferencing bridge infrastructure utilizes packet tagging of encoded packets with a tag as well as adaptive scheduling of bandwidth to transmit packet based information to the end user call participants. Decoding is accomplished at each end user based on information included within the tag such that an appropriate decoding algorithm is selected for the packet-based audio information thereby avoiding tandem vocoding.

Abstract: A method and apparatus that performs specific automatic gain control in an echo canceller (16). The disclosed method and apparatus utilize a low complexity algorithm that performs automatic gain control to achieve greater speed of convergence of the echo canceller (16) and an increased ability to distinguish between near-end speed and echo through the use of specific automatic gain control. A double talk threshold of the echo canceller is adjusted by using, in part, computed gains of inbound and outbound signals internally within the echo canceller in order to adjust the echo canceller double talk threshold.

Abstract: A system and method for controlling echo using zero echo path, ringing, and off-hook detection. When conditions for zero echo path are detected, the present embodiment bypasses echo cancellation by replacing the output signal with the input to the echo canceller. In addition, the present embodiment also provides ringing and off-hook detection which additionally evaluate when the output signal should be replaced by the input to the echo canceller. The system and method provides additional detection and control benefits to echo cancellers and can be implemented in echo cancellation systems without substantial change to the existing echo canceller.

Abstract: In a communication system (100), a first echo return loss through communication system (100) associated with a first call connection between a caller (111) and a first caller (114) is estimated. A second echo return loss associated with a second call connection between caller (111) and a second caller (112) is estimated. The call connection may be switching from the first call connection to the second call connection after estimating the first echo return loss, and from the second call connection to the first call connection after estimating the second echo return loss. Echo generated in the first call connection is cancelled based on at least the first echo return loss by an echo canceller in communication system (100) after switching from the second call connection to the first call connection.