Warid has ultimately started charging balance inquiries made through *100# at 10 paisas plus tax (12 plus including tax). However, call summery will keep showing the remaining balances free of charge.
Warid was the only operator that wasn’t charging balance inquiries till now.
Recently Warid took back SMS delivery reports – while free balance inquiries and SMS delivery reports were unique identifiers of Warid, which are now taken back for un-told reasons.
P.S. Some users on 0321 code are also reporting that their balance inquires are not being charged, maybe due to flaw in system configuration as customer support has confirmed us that *100# is bing charged at 12 paisas per instruction.