Thanks for a portion of advices! Yes, I have my phone turned up fully. I want only to break my radio/media by the messages from navi. As you have your experience it is not possible. Please notice my phone during connection with Jeep does not play any sound. So navi messages is "eaten" by UConnect. Maybe I can turn it on using phone speakers even when my phone is connected with UConnect?
The only way that your phone navigation instructions will interrupt your music is if you are playing the music from your phone. The phone can only interrupt the other apps on the phone. It can't interrupt the satellite radio or the regular radio or other media (like a USB plugged in with music).
You can listen to your radio or other media on the jeep speakers and get phone navi instructions from the phone speakers (so you're hearing both at the same time) .. OR .. you can use your phone as your media and listen to phone music that will be interrupted by the phone navi instructions.
It sounds like what you want (and everybody would probably want) is to listen to the radio or other media AND have the phone interrupt that audio with phone navi instructions. From my understanding and experience, this is not possible. If someone else has been able to make that happen, I'd love to know how.