One hundred twenty-eight (128) Channel Hardware Echo Cancellation Module for use on TE435/436 cards. The Digium VPM128 is compatible with the TE435 T1 PCI Express card. This module eliminates voice echo commonly associated with PSTN's. Echo cancellation software can reduce the echo, but is not always effective. The VPM128 echo cancellation module attaches to the TE435 card and provides effective echo cancellation for up to 128 channels. Note: compatible with the 4-port TE435 card.