SingTel,  M1, StarHub is charging lower rates for prepaid subscribers compared to postpaid users. Calling rates, data roaming rates are substantially lower (>50%). They allow prepaid users to port over to their postpaid but not vice versa. They have been holding us hostage with the non-portability of postpaid numbers over to prepaid. 

Calling rates of 16cents/minute (exclude GST)  compared to 8cents/minute (GST inclusive) 

Need to pay for data roaming package for postpaid users compared to data roam at Singapore local rates for selected countries. 

Charges $5+GST for caller number display compared to free CND for prepaid users. 

It is long overdue for Singapore to have FULL NUMBER PORTABILITY.