The screen displays the ringing bell icon, but the number on the screen never looks like a phone number (today's was 1959954216) and I assume is a code rather than a number.
it also doesn't display the usual format:
But has the one number once and reject / silence options.from number xyz
from number xyz repeated
for ext. abc
reject / silence
When I reject it has a code - I went to take a photo with my mobile, but it cleared before I could. There was some error text and the number 814.
Any ideas what this is and why I get them?