Background noise issue (aggressive cancellation?)

ip-communications

#1

Hi team, we’re installing 28 DP-71x for a customer and are having a problem. The phones are terminated at the OpenVox SIP GSM gateway; the gateway settings are correct because it works just fine with, for example, SIP applications or other SIP endpoints.
The situation: when an employee (A) is calling someone (B) using a DP phone. When A is not talking, B hears silence, probably due to aggressive noise cancellation. Noise is quite high in the room due to all 28 employees speaking at the same time. When A starts talking, the following happens:
a) first few moments of his speech are lost;
b) B hears lots of background noise.
When A stops talking, B hears silence again and thinks that A has dropped the line.

What would be the solution? There are no settings for this in GUI…

Cheers
Alexander