phone conversation sound transfers to my cell phone mid-phone call

[goinelectric]

I've had my car 18 months (with the same android phone), and this just started happening last week.

I receive or make a phone call while driving. All is well. The mic is working, I hear the other person just fine through the car speakers. Then, all of the sudden, the speakers go silent, and I hear the caller's voice coming out of my cellphone. According to my phone settings, I am NOT on speakerphone. I'm paired to the car. According to the car, I'm speaking through the car.
Has anyone ever had this happen? How can I resolve this? It's annoying as heck. Thanks for your input!

 

[Randy-12]

I had this happen once when I was parked and on a long call. It transferred back to my phone after about 40-45 minutes, so I put it down to the turning off.