Click-to-callback is a Web-based customer relationship management (CRM) technology that enables users browsing a company's Web site to leave a phone number where a company representative can call them back with more information.
PeopleTech click-to-call buttons, the buttons, which let people call the owner for free and anonymously, have been quietly in private beta over the past year. The call button is available to registered users and come as a bit of embed code you can put on your web page or at the end of an email. They come with several customizations. You can adjust the CSS styling, adjust the number it calls, and restrict which countries can try to call you.
When users click the button, the caller enters their phone number and page connects the two parties over a VOIP line or with PSTN/TDM line. The callee is then told who called and asked if they want to accept the call, say they’re busy, or blacklist the number. If they accept the call, the minutes are charged to their account. It can be used for some cheap long distance calling.