When I get calls I can't either answer nor reject the calls

Since your iphone is still under warranty, have it inspected at an Apple Store or Authorized Service Provider:

Apple – Location Selector

Regards

Giulio

1. Launch the Settings app.
2. Tap General.
3. Tap Reset. It's all the way at the bottom.
4. Reset all settings

this should solve your problem, well if the problem is... the phone freezes when you recieve a call

Purchased my iPhone about 3 weeks ago. Performed the 12.4 update. Now my phone doesn't make/receive calls, Bluetooth nor Wifi work. Called Apple support; they had me go through the resets again with no luck. Support gave me instructions on how to do a factory reset via iTunes. I performed the full system recovery, wiping everything out, didn't fix the problem because once 12.4 is on your phone, it doesn't go away. In the last 2.5 years, I've purchased a total of 5 iPhones. Three of which the battery was defective in less than 30 days, the 4th was ok, and this one, as stated before, is 3 weeks old and useless. Apple has received the last penny from me they will ever see. I'm done with this company.

I tried the forced start but it didn't solve the problem. Someone posted that he had his phone "announce" his calls and his phone wouldn't work now. I sent into Settings and turned the phone on to announce my calls and then turned it off since I don't need my calls announced. My phone mysteriously started working. Probably not a solution but it worked for me. Waiting for 2 1/2 hours at the Apple store was not a solution for me.

Try a forced restart of your XS:--> Force restart iPhone - Apple Support

Regards

Giulio

You're welcome

I have this same problem. Cannot receive calls nor make them.

I tried the forced start but it didn’t solve the problem.

I have this problem too can't answer the phone and it is locked.

power off gets back to strandard use till next call iseceived

Hey! I’m experiencing the same issue. Were you able to fix it somehow?

I’ve tried all kinds of resets and have even erased all contents and settings and set up my iphone again, but the problem is still there.