Click-to-call (CTC) refers to the process of converting web-based traffic into direct telephony communication between an end user and some other entity. CTC originates out of the older PC2PC telephony whereby a client is downloaded onto your own PC to "talk" to the same client downloaded into the other party's PC for the conversation (with vendors such as Net2Phone).
In this implementation, these services tend to be more of an automatic dialing service than an actual "click-to-call". This is normally known as "Auto Dialer" mode whereby the service is only helping the user from the dialing of the other phone number. The other style is callback whereby once the name and phone number of the user are obtained, the intermediary service is calling the merchant first, and then connect the merchant to the end user. InsideSales.com is an example vendor of this style. In this mode, there are many benefits presented to the end users depending on the vendor. Some would provide you with guarantee connect using their find-me-follow-me algorithm in the back end to make sure at least one agent from the merchant side is found to talk to the end user. Some would provide a courtesy call back even if nobody can be found. But all will save the end user from waiting on the phone to find out that there is nobody on the other line since the CTC was triggered at two o'clock in the morning for the merchant.
One significant benefit of click-to-call providers is that it allows companies to monitor when online visitors change from the website to a phone sales channel.
In November 2006, Google experimented with a callback process in its Google Maps product but eventually removed the feature . As of January 2008, Google is testing click-to-call for businesses listed in search result pages . Some people have indicated that such failure is due to the fact that Google is using the CTC in the Auto Dialer mode, providing very little benefits to the end users. Other vendors who provide CallBack mode fare differently such as Ingenio was acquired by AT&T Yellow Pages and eStara was acquired by ATG.