when u send a global sms from singapore to someone on a foreign
mobile number it only costs 0.15 cents.
if ur sister is holding a singapore mobile on roaming, it costs u
normal sms charges which is 0.05 cents. so dun fret 
sms charges costs alot only when ur roaming & intending to send
a message back. so as long as ur on local soil & logged on to
ur home network here, charges are not that expensive
