Today, M1 issued a short News Release stating that they are offering Prepaid to Postpaid porting while retaining their mobile numbers. So, for existing M1 prepaid mobile customers, you can visit any of the 15 M1 Shops island-wide from today for this service.
This is actually not something new. StarHub has announced this service last month. More information in the News Release.
Here is the News Release
M1 to offer Prepaid to Postpaid Porting
SINGAPORE, 24 July 2013 – M1 Limited (M1) today announced that Singapore prepaid mobile customers will be able to retain their mobile numbers when they upgrade to a M1 postpaid plan.
Prepaid mobile customers who wish to convert their plans can visit any of our 15 conveniently located M1 Shop outlets for assistance, from today. For more information on how to enjoy the perks of M1’s postpaid plans, please visit www.m1.com.sg/porting.