If you do the calculations and read the fine-print right, you will notice that you will be charged airtime for those calls, typically around 15.75 cents or more per minute, so your "free" call is not really free... Our rates are pretty competitive and for some countries it'll be cheaper to use our callback than to use the "free" usage of the mobile provider.

It happens that for instance in Malaysia when roaming with some providers you can't trigger a callback like you used to do in Singapore. This can be resolved by using *121 (in the case of Singtel) or simply use SMS callback where you give the command "Call to our SMS centre... That will work in most cases.

Yes, compared to normal roaming charges you can still save up to 50% more using our service, especially if you call countries other than Singapore from where you are. One could use *121 to call Singapore (or your providers' equivalent), the price difference there would not be so great, but for calling every other country from outside Singapore it's definitely better to use our service (as the mobile provider would apply the standard 001 rates).