Both starhub and singtel are feasible de!
I using M1 one and it drains me like crazy.
Starhub got free 10sms with 5 sent, M1 don't have.
Plus M1 per min billing, 1 min 16 cents in the day
Last time I call someone, then unreachable (I called 3 secs only), reached her "mailbox" m1 also deduct me 16cents, but i blur blur dunno call 3 times all reach her "mail box", then m1 deduct me 16centsx3!!