The blank white screen problem occurred on my iPhone 6+ after updating to 12.0.1 (from 12.0.0). As others have indicated, I was able to receive calls.
After restarting iPhone, logging in/out of iTunes, etc the Phone App white screen persisted.
Took my phone to my wireless provider (Verizon) as previously suggested to have the SIM card swapped out.
The SIM swap out fixed the problem.
iPhone 6 Plus, iOS 12.0.1
This is happening to me, too, after the 12.0.1 update.
I also use Verizon, but before I try to find a store (I'm on vacation now), I'd like to see if you know of any other fixes that you (or others) have come across.
Thanks in advance.
Dwayne
I tried other fixes as mentioned and none worked. I expect (but did not try) dropping back to 12.0.0 would work, if you have an iTunes image. For me a SIM swap out was a quick and low risk thing to try since I had a support contract on the phone.
Also I assume a 12.0.2 update is coming, but any fixes on older phones is TBD.
My phone app gives me a blank white screen. -redux
