Digium 1VPMOCT256LF 256 Channel Echo Cancellation Module

The Digium 1VPMOCT256LF is a 256 channel echo cancellation module. For Asterisk users who connect to the PSTN, the most common type of echo is hybrid echo - the echo introduced by the impedance mismatch between 2-wire and 4-wire telephone circuits. The echo manifests as a distorted and delayed reflection of the users voice while in conversation with an external party through the PSTN. Asterisk itself offers a range of software-based open source echo cancellation routines that are moderately effective in eliminating the hybrid mismatch echo that most Asterisk users experience.