I was having consistent troubles with my GMC Acadia (I could get it to pair but when I tried dialing out or someone would call in the call would drop off bluetooth and back to my phone). After several calls to Apple and reading boards here I finally got it to work.
Before I get into that I will tell you that I found an article yesterday that with the new IOS 8 update scheduled to be released at the end of October where this problem will also be addressed with the update.
Okay here are a few things that I did that somehow finally have gotten it to work consistently.
1) Delete all your phones from your car blue tooth list .
2) Delete your car from your phone. Settings blue tooth by your car there should be an "i" press that and hit forget this device.
3) Reset your network settings. Settings- General - Reset - Reset network settings
I finally got it to work this way but once I powered down the phone the problem came back (but I have read where this worked for people and stayed working)
Next this is what I did that has solved my problem for the time being with no issues (fingers crossed).
Did all 3 steps above but I also went to Settings - General- Reset and Rest all Settings ( I backed up my phone to be on the safe side but I didn't lose any contacts, apps, etc.) It just sets all your settings to what you started out with...like ring tones, location services, etc.
Did a hard reset on my phone after that then re paired the phone, etc. and now it works!!
Hope that helps.
