- I think it have to replace SimpleTimer to e.g. CounTimer for the display control because I will re-use the timers and seems to me that SimpleTimer does not support it: "After f has been called, the interval is deleted, therefore the value timerId is no longer valid."

- I did not found JVC commands for the short press phone button and volume knob press. It means I cannot initiate any calls and I cannot terminate them. I found command for long press of phone button but it reject the call. JVC supports voice control but I am afraid it would be very unreliable (in Hungarian language) and very unconfortable and dangerous during driving if it recognizes wrong names and/or commands. Therefore I think I will use bluetooth. If anyone has knowledge or hints on it please share with me. My plan is that arduino will connect to my phone (Honor 9) via Bluetooth, read the contact list (send it to Clio's display) one by one. Then I will be able to initiate and terminate calls with a remote control button. At this point I do not know how should I start. Which bluetooth shield/module do I need or is it even possible. But I hope so ;)

Unfortunately I did not find any similar project yet.