Samsung MM A880 - Manual (Page 218)

210 Section 3A: Sprint PCS Service Features: The Basics
Using Caller ID
Caller ID allows people to identify a caller before answering
the phone by displaying the number of the incoming call. If
you do not want your number displayed when you make a
call, just follow these easy steps.
To block your phone number from being displayed for a specific
outgoing call:
1. Press .
2. Enter the number you want to call.
3. Press .
To permanently block your number, call Sprint Customer
Service.