PRI low audio problem on forwarded calls

The system is FPBX 2.10 with Asterisk 1.8 I know it needs to be updated, and we will work on that. All aspects of the system operation is fine. The only is when a user will forward their phone to their cell phone. The audio is so low they need to run the volume on the cell phone to the max and then it isn’t quite enough. The Dahdi version is 2.6 I tried to improve the audio by adjusting the Rec/Xmit to +3 to see if there was any improvement, there wasn’t any. So theoretically there shouldn’t be any loss through the system right? We will get started on getting them upgraded. Any ideas appreciated.

If it only happens on Cell Phone calls, I’d have to guess that the problem is outside your control.

I am going to try and recreate it on another system. But I am pretty sure you are right. Thanks for the input