IF it is the same device as Gigaset DESK 800A then it should have CLIP.
Then the phone book is retrieved from tel.search.ch and the entry found there is also displayed.
I have a Gigaset C610 wireless phone that displays this. Ingenious.

If the telephone number with name has been saved in the phone's address book, the telephone number with name is displayed when a call is made. Otherwise, only the phone number is displayed.