[asterisk-users] adding second TDM400P card causes echo cancellation to fail for all Zap channels

[Stephen Bosch]

Hi, folks:

Yesterday I added a second TDM400P card to a working, echo-free server
running HPEC.

Today, I'm getting these messages:

> Apr 20 09:12:12 WARNING[5679]: chan_zap.c:1551 zt_enable_ec: Unable to enable echo cancellation on channel 3

along with complaints of severe echo. The channels have all been tuned
using 'fxotune -s' and the echo numbers are all under 2%. I guess that
Asterisk can't do echo cancellation on these channels.

Why would I be getting this?

Thanks,

-Stephen-