CallsUp! is a mobile applications that automatically detects the best call mode to give the user the best rate for a given call. The service also is avaialble for landlines and mobile phones without Internet access. An API is available for developers to offer their customers the service's functionality directly from their website. Public documentation is not avaialble.
The following is a list of how-to and tutorial content that matched your search term. ProgrammableWeb's how-to content comes from two sources; full-blown tutorials that we publish ourselves and other highly relevant tutorials that we find elsewhere on the Web. This list represents on combination of both tutorial types and if you go to ProgrammableWeb's API University, you'll not only be able to find more, they are organized based on your role (API providers or developers who consumes APIs). If you know of a tutorial that would be of interest to the ProgrammableWeb community, we'd like to know about it. Be sure to check our guidelines for making contributions to ProgrammableWeb.