Abstract: An audio codec capable of handling complex control and routing of numerous sound inputs is described. The complex control and routing is obtained by weighting various sound inputs in accordance with weighting values and then digitally mixing the weighted sound inputs together. The invention facilitates construction of the audio codec with mainly fixed gain amplifiers, instead of variable gain preamplifiers, thereby saving a large amount of die space and reducing time needed for testing.

Abstract: A Voice Response Unit (VRU) 10 provides ports 12 to which communications devices 13 may be coupled. Two-way conversations between ports 12 are enabled by inter-port connections made by system bus 16 as controlled by distributed switch 15. Summation resources 25, permanently inserted in signal paths to and from ports 12, provide digital summers 33A, 33B and 33C that then permit signal processing resource 22 to be conferenced in on said two-way conversations without having to route signals through conference bridge resources.

Abstract: The disclosed invention constitutes a method and system, including an audio mixer, for selecting audio streams from one or more applications running on a computer system. An application can register its audio streams with the audio mixer either as sound focus audio streams or as priority audio streams. With respect to the sound focus audio streams, the audio mixer determines which of the applications has the sound focus and generates an audio output signal from those sound focus audio streams to drive the computer's sound device and thereby to produce an audible sound for the user. Sound focus is determined when an application gains the input focus, opens an audio stream, closes an audio stream, or registers with the audio mixer. With respect to the priority audio streams, those priority audio streams are always selected by the audio mixer and are mixed with the sound focus audio streams from the application having sound focus to generate a composite audio output signal.

Abstract: A digital private branch exchange system and methods of operating same are provided. A system is capable of providing improved and integrated conferece calling, voice mail, music on hold, and call forwarding features, without being subject to the typical problems associated with the prior art.