Tfonia is OK - $1 for a free account but covers only USA/Canada/UK. For Europe and other other countries it's 20% revenue share ( list of the current countries : Canada, Australia, UK, USA, Austria, Denmark, Finland, France, Germany, Hong Kong, Ireland, Israel, japan, south Korea, Liechtenstein, Monaco, Netherlands, Portugal, Saudi Arabia, Singapore, Spain, Sweden, Switzerland, United Arab Emirates) . For other phone sex affiliated networks
check this site.