The 3 billers mentioned above Global Access, No Credit Card, and Itelecharge are all integrated with NATS and can be easily setup in your NATS cascade to use for processing with your sites.
Let me know if you have some time to discuss getting your affiliate program going with NATS and mobile billing.
vlad[at]toomuchmedia.com
732-385-1536 XT 1123
ICQ - 452583619
AIM - TMMVlad
Skype - TMMVlad