There are two forms of Calling Line Identity: the first is Calling Line Identity Presentation (CLIP), which displays the cellphone number of the person who is calling before you answer. If you have stored the caller's name and number in your contact list, it will automatically show his or her details as saved on the handset.
The second is Calling Line Identity Restriction (CLIR), which prevents your cellphone number from showing on other handsets when making a call. One can assume then that only numbers that are not restricted will display on handsets where CLIP is activated.
Calling Line Identity is free and can be activated or deactivated by calling Customer Services. Alternatively, consult your handset user manual for more information on CLIP and CLIR.
CLIP will allow you to see the number that is calling you provided it is not restricted (and your number will be shown when dialing out).
CLIR will prevent your number from being viewed when making outgoing calls (and you will not see an incoming call number).
*Please note: this service is phone specific. Instructions for activating may vary. Please check your phone manual if you don’t see the above options on your phone.