iPhone XS Max and 2016 Toyota Tundra

I have a 2016 Toyota tundra and I use a iPhone XS Max to connect to my tundra. I have no problem streaming music are receiving text, but if I try to talk hands-free while connected to the truck my calls drop every time. I have taken it to Toyota and Toyota is telling me that it is a software issue with the Apple phones and that they would only work with the ISO 12.0.1 software. I have downloaded the newest iOS software Hoping there was a fix for this and I still drop calls. Is there a fax for this because I’m getting sick of talking on the phones speaker and not through the stereo system.