For Android phones:
STEP 1: Tap the phone icon/widget to go the dialing screen.
STEP 2: Tap the "menu" button which is on the lower left side of your phone, beside the Home button.
STEP 3: Go to > Settings > Call > Call settings > Additional settings > Caller ID
Step 4: Select Hide number/Show number.
Note: It is advised to always keep your caller ID settings at the network default.
STEP 1: Go to Settings > Phone > Show my caller ID
STEP 2: Slide the toggle in the right to activate