Originally Posted by jbfield
Bear in mind that with SingTel at least, the pre-paid credit cannot be topped-up by yourself when you are not in Singapore unless you have a Singapore bank account (and internet access).
It is possible to get someone else who is in Singapore to do this whilst you're in Malaysia but they'll need a Singtel account too.
Hmmmm....i thought you can buy a top up card at any 7/11, call the CS number on the back of the card, input your tel number and then the top up card pin?
Also, keep in mind once you top up, the pre-paid is good for another 6 months.
At least all of above was true when I used prepaid.
Since OP is spending most of his time in malaysia, better to consider malaysian alternatives, once again, check www.prepaidgsm.net!