For Prepaid:
Opt-in:
Keyword: START E or dial *111*8*5#
Port: 5544
Reply SMS: You will get notification in the phone display, after every voice calls you make.
Opt-out:
Keyword: STOP E or dial *111*8*6#.
Port: 5544
Reply SMS: You have stopped getting information in phone display, after every voice calls you make.
For Post-paid:
Opt in: *121*1001*1#
Opt out: *121*1001*2#