I have searched and found similar but not the same problem I am having.

I have a Z2 with BT adapter and an iPhone 3GS.

When I receive a call I can almost hear the caller... I have the phone volume at max in the Z2.

Any ideas??

When connected on a call turn the iPhone volume up then delete the phone from the unit and re-pair it.

Thanks... I'll give it try.

also turn the HU's phone volume all the way up, BEFORE re-pairing it....

IMO the Iphone has a flaw in this department, as in, you HAVE to be one BT connected call to be able to turn it's BT volume up