Question : Echo on Trixbox with Digium TE122B PRI Card.

I have a Digium TE122B PRI card in my Trixbox 2.8 (Asterisk 1.6) system.  When calls are made, I get a very noticeable echo after everything that is said.  The echo is only heard by us, and only when we speak, not when the called party speaks.  This board has onboard hardware echo cancellation.  How do I make the echo go away?

Thank you

Answer : Echo on Trixbox with Digium TE122B PRI Card.

Have you tried turning the echo cancellation off on your Digium PRI card? It may seem like a daft thing to do, but it is best if echo cancellation is only operating at one end of the path and chances are that your telco is already providing it. There is a setting in /etc/asterisk/chan_dahdi.conf that can be used to disable echo cancellation.

Another thing to try is adjusting the setting for LBO in /etc/dahdi/system.conf:
# span=<span num>,<timing source>,<line build out (LBO)>,<framing>,<coding>[,yellow]

# The line build-out (or LBO) is an integer, from the following table:
#  0: 0 db (CSU) / 0-133 feet (DSX-1)
#  1: 133-266 feet (DSX-1)
#  2: 266-399 feet (DSX-1)
#  3: 399-533 feet (DSX-1)
#  4: 533-655 feet (DSX-1)
#  5: -7.5db (CSU)
#  6: -15db (CSU)
#  7: -22.5db (CSU)

Try different values and see if it makes a difference.