Which SMS payment service allows you to set an arbitrary price for each purchase, rather than a fixed one?

Question

Payment systems

Conditional problem on the old example. Let's say there is a site with ringtones for the phone and each ringtone has its own price. What service can be used today to accept payments for digital goods via SMS? Who has the best quality of services and the lowest commission? How many times a month can I withdraw funds from purchases from such a service? What are the pitfalls of Russian business with payment by SMS present today? The service should return to my server the id of the ringtone and the phone number of the person who made the purchase.