Set up as a bulk sms service, but private users can also use it. It takes some time to understand it completely and you have to put some credit (by credit card) on this account but if all is set up u can easily send sms (with confirmation report) to most Indonesian providers:
Satelindo (Mentari etc): 4,4 eurocents/sms
Telkomsel (Simpati etc): 4,4 eurocents/sms
Excelcomindo (ProXL etc): 3,6 eurocents/sms
Im using it for 3 years now, its a wonderful service, 100% reliable, and you can even change ur own ID (Send ID) and schedule sms for later delivery for free. Good luck!