I've just recently picked up the iPhone 11. I always connect it to the NAV,connects first time and overtime takes calls through that ,should i need them . I made a small file of the numbers of family members, should they need to contact me. so thats all that will ring on the phone. work numbers and random numbers go straight to voicemail ,so i can pick them up when not riding.
One issue with the TFT/Iphone is that the TFT cannot handle alot of contacts. So make a small list of those who you dont mind contacting you on the phone and then try then. If however, you have to have the whole phone directory connected ,you still struggle with it on the TFT. Like i said the Nav 6 will take then all if you need it .