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Knowledge Base / Hardware / Why do I hear echo when I make a call?

Why do I hear echo when I make a call?
Views: 13558, Votes: 1

Posted:
12 Mar, 2006 - Brooks M.

Updated:
14 Mar, 2008 - Support D.
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In the analog phone world, FXS and FXO interfaces combine the receive and transmit signal on a single pair using a device called a hybrid. Because the transmitted and received signal are on the same pair, part of the transmitted signal comes back along with the received signal.  To resolve echo problems, you will need to set "echotraining=800" and "echocancel=256" in zapata.conf.  If the voice quality is bad, you will need to decrease echocancel by a factor of two and repeat until voice quality improves.  After you have discovered the correct value for echocancel, you can change echotraining until you get the best quality.
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