[Asterisk-Users] Wits end with echo

[Jon Reynolds]

Hello,

I have an AAH-1.5 with a TMD400P with four lines, 8 Grandstream GXP-2000 
phones, I am having echo issues on the GXP-2000 side.

Here is what I have tried so far:

The server has everything in the bios turned off except what is needed, 
USB, LPT, Serial etc,etc.

I have uncommented Echo Suppresion in zconfig.h and shutdown and turned 
back on the asterisk box.

I have updated the phones to 1.0.12 firmware, I have echotraining=800, 
echocancel=yes, echowhenbridged=yes, in my sip.conf file. I am using 
Mark2 as the echo suppresion and still I have echo.

All the phones have been wired straight to the cisco 2950 switch and all 
cables have been tested and found to be good.

I am completely at a loss at this point as to where to start looking and 
working to fix the problem. I would like to switch from Mark2 to MG1 but 
I don't know how I would acomplish that with AAH. I have played with the 
rx and tx gain but after reading multiple docs on it am still unsure how 
this would help and how to adjust it using /usr/bin/ztmonitor 1 -v.

If anybody could point me in a new direction or something else to look 
at or something more to read that I may have missed I would be very 
appreciative.

Thanks for any help,

Jon