Starhub Green Prepaid Card - Roaming Overseas

Roaming Coverage
I would think the roaming coverage would be comprehensive but the detailed count should be more than 100 countries.

To activate
Dial *111# before leaving Singapore

To top up overseas
Dial *112*(10 digit top-up number)*(6 digit PIN)#

How do I make and receive calls and SMS?
Sending and receiving SMS is very much the same experience you have while using it in Singapore. So is it for receiving calls - you just answer it.

But outgoing calls is made using a call back service. To put it simply, you need to know how to dial properly.

You need to dial according to this format - *123*(country code)(phone number)#. The starting string (*123*) and the ending character "#" is important. So is the country code and mobile number of your friend you are calling.

Checking Account Balance
Dial *113# to know how much more you have left.

This pretty much sums up the key parts you should know to get you started. More info and actual rates refer here