My iPhone hangs up when I press number options on a call

Hello ~ Take a look here for some things that may help:

Restart your iPhone

Update your iPhone, iPad, or iPod touch

If these don’t help go to upper right hand corner and click on Get Support for further assistance.

~Katana-San~

See if it was a temporary glitch performing a "forced" restart of your iPhone, as per these instructions:--> Force restart iPhone – Apple Support

Regards

Giulio