Dialogic Corporation

Prabhakar Chitrapu

Wei Lin

Chris A Hamilton

Chet Juall

Andrew Dumont

Zhibing Pan

Mark Ulrich

An improved system for minimizing toll charges is disclosed wherein line quality is measured and a call is terminated if the line quality is not at an acceptable level to allow for the highest possible bit rates during data transfer or to guarantee a certain minimum degree of quality.

Technique of controlling telephone calls

A technique for utilization of call processing resources in a call processing system is disclosed wherein echo characteristics of a telephone line ascertained and utilized by a echo canceler, and are also stored for subsequent use by a different echo canceler which processes a call on that same telephone line. The technique may also be used with call processing resources other than echo cancelers.

Call processing using previously obtained line characteristics

A tone blocking system and method for use preferably in conferencing systems in order to prevent control tones from being transmitted to other conferees is disclosed. The buffer length used to process the signal and detect tones is varied, being increased when a tone is suspected to allow for sophisticated tone detection algorithms, and being decreased when silence is present by trimming the silence away. The technique minimizes delay, and its degrading effect on echo, but nonetheless provides for a lengthy buffer required to do reliable tone detection. The invention is applicable to any signal other than tone as well.

Tone blocking using variable delay buffer

A tone blocking system for use preferably in conferencing systems in order to prevent control tones from being transmitted to other conferees is disclosed. The buffer length used to process the signal and detect tones is varied, being increased when a tone is suspected to allow for sophisticated tone detection algorithms, and being decreased when silence is present by trimming the silence away. The technique minimizes delay, and its degrading effect on echo, but nonetheless provides for a lengthy buffer required to do reliable tone detection. The invention is applicable to any signal other than tone as well.

A technique for software ring tone detection is disclosed utilizing, in the preferred embodiment, a recursive algorithm. The technique provides flexibility in that a digital signal processor may be reprogrammed to detect ring tone frequencies and amplitudes present in numerous different countries.

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Princeton, NJ, United States of America

Prabhakar Chitrapu