Dellmont provide dollar and Euro billing program.
If you make a reseller ID in one program then you can send credit to all the program(about 70 program). Its better to make 2 reseller ID, one in dollar billing and another in Euro billing. You can send credit from your Euro billing reseller ID to dollar billing customer ID but the credit will be converted to dollar according to the current exchange rate. You can use the reseller ID as a normal ID that means you can call and send sms from you reseller ID.
You can create your reseller ID yourself and start reselling with in second.
You can buy minimum 10 euro for your reseller ID so the minimum investment amount is only 10 Euro. There is no time limit to sell the credit and there is no risk because if you can not sell then you can use the credit for yourself.