VPMADT032 echo cancellation module is meant to be used with the Digium IP telephony boards; it provides echo cancellation for configurable long "tail" of up to 128 ms (1024 samples) simultaneously for all ports of the board. All IP-PBX Asterisk servers, connected to the telephone network (PSTN) have one common problem, which is "hybrid echo" - echo obtained due to the difference in the load-wire and four-wire telephone circuits. Echo appears as a distorted reflection and a detainee of the caller's voice, who is subscribed to IP-PBX Asterisk while talking to PSTN subscribers.
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