The following module enables you to provide your website users with paid registration via SMS-message
The moment user is forwarded to the payment page, he will be offered to send an SMS.
Following the message sent and initial activation of the password received in reply message,
user will be able to complete the registration.
On smscoin.net website under sms:key service settings you can set the lifespan of generated password
as well as the number of times it could be activated.
To use the following module you first must register on SmsCoin.net website, as well connecting
sms:key service.
Registration and setup process are absolutely free.
Link: download