I think I need to explain the setup before the question will make any sense.

The scenario is:
Mitel SX-200 ML at a hotel with an incoming T1 from telco. Calls for Reservations are forwarded off site to a call center application via a LS trunk in the Mitel that connects to an Adtran 924. (FXS port in the Adtran) The Adtran uses SIP to connect to the remote Call Center. If the call needs to be rerouted back to this hotel, they return it via a specific channel of the Adtran which connects to a specific trunk in the Mitel that is DIL via Form 14 to a specific station/agent.

The problem:
It works surprisingly well except that the station/agent at the hotel that receives a call via this route is hearing some local echo/feedback in their handset. The original incoming caller does not hear any echo.

The Call Center techs are asking if I have any way to reduce the mic gain on these trunks/lines in the Mitel.

I'm at a loss with this one.
(pardon the pun)

There's nothing in the Mitel to adjust. The echo is being introduced through the Adtran and or the equipment between the Adtran and the reservation center, most likely the ISP provider the SIP is running. You could adjust the T1, but then you would be introducing loss, etc. for the entire span which would no be a good thing. Contact the owner of the Adtran and see if they can make adjustments for echo reduction.

Rcaman

Thanks for the quick response.

That is the direction I was leaning too. But since the Adtran and SIP trunk were provided by the reservations center, I "Assumed" that they would try that first.

Thought I would check with the panel of experts.

I had a fleeting hope that the trunk circuit descriptor entries for "Toll Office" and "Is this a CO" would help. They both refer to adding pads/db-loss. But the doc refers me to the Engineering section that I can't decipher.

You have to be careful with echo. Line build out is where one normally goes to reduce or eliminate echo. Adding/deleting loss can make more problems than it solves. Some software driven channel units use software to mimic LBO. You might look there.

Rcaman

This was resolved via adjustments in the Adtran gateway. (Sorry, I don't know what they changed)

My apologies for not posting the resolution sooner.