when your phone is registering to a network, a small amount data packets will be exchanged during the handshake. most malaysian telcos will consider this a valid data use and will charge you. if you are lucky, you will be charged data roaming per pay use and lose rm3-4, or if unlucky, the data use will activate a roaming package and lose rm10 or rm38.

xpax's recent data roaming offerings now will waive the first 10k of data. i guess they are acknowledging the issue.