I can receive phone calls and hear but cannot answer back

[Android Central Question]

I've tried 2 different phones thru my Mercedes sprinter van and both will accept phone calls but cannot answer them.

 

[B. Diddy]

Welcome to Android Central! Does the van have Android Auto, or are you using a basic Bluetooth interface with the van's stereo system? If you get a call, do you get an option to answer the call, either on the phone or on the van's system?