Dan makes a good point of just turning off the BT on the Nav IV. You've already got it hard wired into the equation so you'll hear turn by turn directions. You are giving up on screen phone controls, but as it sits there's no way to do that with what you have. That really is the main issue here and why this is so difficult. If it was like any other GPS that could pair on the Phone only side, we wouldn't be having this conversation, but it just can't. BTW, you mentioned pairing only the GPS & Phone. While that will work and allow you to see who's calling if you get a call, you really have no way to communicate through the GPS to the phone with nothing else connected, so you can't really talk on the phone with that setup anyways. Doesn't seem that feasible So I guess your options are. 1. Turn of the BT on the Nav IV and just have the turn by turn directions as you have it setup now. Have your phone directly connected to the SMH10 2. Purchase the SR10 and add in to gain full phone control via the GPS and voice which you are missing.