Click the button and call a Jajah user for free
Jajah lets you make free calls to other users, or low-cost calls to phones using a web-based VoIP service. We have covered them before here with their low cost mobile web service.
With the new Jajah Button service, users can place a button on a website, blog, social network or in email signatures through an embed code and will be able to accept calls. This button will automatically connect the presser without giving out a phone number. Don't feel like answering the call? Reject it, or even block specific numbers. Again, if the button presser is a Jajah user, the call will be free. But there will be a charge per minute if they are not, that's were restrictions can be implemented.
Jangl also provides a similar service.