Car Audio: Bluetooth pairing for phone calls does not work on Pinephone postmarketOS on the car audio system for Toyota RAV4 2017 model

Not sure if this is an enhancement request or an issue. The car audio system on the Toyota RAV4 2017 model is not one of the modern Apple Play, Android audio or Alexa audio systems. I tried to pair to pair the Pinephone Community Edition PostmarketOS edition. I could only pair it for audio playback for music/video/podcasts. But it does not pair for phone calls - the car system says that phone call pairing is not supported.