Lets you see who's calling before you answer (as long as the number isn't withheld).
You can also use Caller Display to avoid nuisance or cold calls.
How do I set up Caller Display?
Caller Display is free of charge for all Shell Energy Broadband phone customers but you’ll need a caller display capable phone to use the service.
My phone is not displaying every number that calls me
If a caller has withheld their number it will not appear on your handset. You can try and call your home telephone from a number that you know isn’t withheld to test this.