most mobile traffic is sent to a mobile site. On there they have ways to buy a membership. How do they buy it? Credit card just like a regular porn site, but right from their cell. No need to go on a regular PC, sign up than go to the site on your cell.. That would be pointless.
For example.
http://www.ipinkvisualpass.com which is one of our mobile sites. You will see that there is a join button and after that you get the form to enter your CC info and all that.
If you want we can set up a whitelabel for you that promotes 1 of our mobile sites. If you have a Top Bucks account hit me up on ICQ. Hell, hit me up even if you don't have a Top Bucks account.