I am raising this issue for everyone's awareness, especially for those with elderly parents or grandparents using smart phones. My 70-year old mother uses a non-smart phone, subscribing to Singtel’s voice call only plan (3G Classic 100). On 5 Aug this year, she tried switching to a new smart phone and inserted her SIM card into the new phone. Unknown to her, the data roaming function in the new phone was activated and she ended up using 50MB of data. Singtel is billing her $256.50 for the 50MB of data usage.