Re: call volume
You can try adjusting the gain on the 3102 but you risk echo problems, if you go too far. Make your you write down any settings that you change so you can go back to the original. Make sure that the impedance settings are correct for your location.
If you are lucky enough to have a second phone line available, try plugging the 3102 onto that and see if there is a difference. Make sure that you don't have any other devices sharing the same phone line, or long, unterminated runs half tapped on the cable pair, the capacitance can reduce level or cause echo problems.