Volume problem on SP350 softphones and USB wireless headsets

[phadobas]

We have completed the setup of a new Call Center and we are using SP350 soft-phones on thin-clients on our SV8500. All the Thin-clients have a USB wireless headset connected. The model is Sennheiser Office SD Pro2.
The volume on the headset is a problem: the called person can barely hear the caller. The microphone volume is set to highest on the softphone as well as in Windows 7 control panel audio settings. Also, the charging base has a microphone volume setting which is set to the highest. Still the called person is not hearing the caller comfortably on local calls, and international calls continue to generate complaints from the called parties: they can barely hear the caller. The caller can hear the other side just fine. I have a feeling that there could be a setting that I'm missing either on the SV8500 (maybe PAD settings specific to the softphone?) or something else.
Does anybody have any idea?

 

[belevedere]

･Voyager510-USB The call control button of the headset cannot be used.
･VoyagerPro-UC The call control button of the headset cannot be used.
･SAVI-GO The call control button of the headset cannot be used.
･HW251N+DA45R
･HW251N+DA45
･HW251N+DA40R
･H251N+DA40
･DSP400 HEADSET-NE (A firmware upgrade is required.)
These are the headsets suggested by NEC. You might try one to see if it is a compatibility issue. It would seem like it should not matter as it is a USB to PC/operating system issue, but you never know.

 

[phadobas]

This is now solved. Command APDIL allows setting PAD values for different types of calls. But to enable this command, you have to set ASYDL, Sys=1, Index 825, Bit0=1 and Bit1=0.

Only after the ASYDL change (which was 00H for me), the volume dramatically increased even without doing anything with APDIL.