There are some options. Unfortunately due to the fact that there is no 'global' option you would have to check if your country is supported. You can try here. This is a plugin for wordpress from smscoin.com
http://wordpress.org/extend/plugins/sms-paid-content/
Be aware that on average more than 50% of your revenue will disappear while being sent from your customer to you
This is because the people running the smscoin website need money and because the telecom provider also needs money.
http://wordpress.org/extend/plugins/sms-paid-content/
Unfortunately my tropical little island is not supported.
Good luck!