Calls not working with Android Auto

[TheRealDarren]

Got a headunit in my car that supports AndroAndroid Auto and it works really well and connects automatically. Can use my apps and sounds great. Except when I try to answer or call people. The headunit shows the call but it's not putting the audio through headunit even though it shows the call is using Bluetooth. Frustrating as I cannot use phone now since I usually keep phone in my bag or pocket thanks to the Android Auto. 

[Kevin1972]

Android Auto music, apps, including incoming calls work fine. However when I make a call (outgoing) I need to physically switch the Bluetooth, using my phone, from "BT182" (my head unit) to "MB Bluetooth" (my car). This defeats the object of 'handsfree'. 

I do not know if it is my Samsung S24, Android Auto or my car not switching the Bluetooth. It switches for outgoing calls. 

Any suggestions or fixes? 

[TheRealDarren]

I'm going to borrow a handset by another manufacturer and see if that works.

[Almazv]

Same problem for pair S24-VW Tiguan. No problem with iphobe on the same car

[Almazv]

Google search shows that there are a lot of people facing the same problem if they connect phone to car using USB cable. Strange, but it requires bluetooth connection for phone audio.

[TheRealDarren]

I use the WiFi mode. Starts connection from Bluetooth but switches to a personal hotspot connection on head unit.