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.
IDC projected over 9 billion minutes of voice traffic to travel over worldwide packet networks in 2000, exceeding 135 billion minutes in 2004. Service revenue is projected at 1.6 billion in 2000 and 18.7 billion in 2004.