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.
In order to meet the needs of users of all analog cards in excellent quality of echo cancellation, regardless of the possibility of installing the echo cancellation module, engineers of Digium Inc have developed a software version of the echo cancellation algorithm. Designed to work on 32-bit operating Linux systems, the program High Performance Echo Canceller (HPEC) provides anti-echo on custom long "tail" in 16 ms (128 samples), 32 ms (256 samples), 64 ms (512 samples) and 128 ms (1024 samples).
However, there are cases where these algorithms are not effective. In this situation, Digium offers the use of a multiport T1/E1/J1 and analog 24-port hardware echo cancellation module. Given module is a replacement for obsolete echo cancellation module VPM100M, which could offer treatment of "tails" only up to 32ms. VPMADT032 fully supports G.168 specification and is based on the Digium HPEC program. VPMADT032 is independent of performance and CPU utilization of the system, as opposed to software solutions.