Talkray is a mobile application created by TiKL, a company also known for its TiKL Touch To Talk walkie-talkie application for Android and iPhone. Talkray is the company's broader communications app that allows users to make phone calls as well as send and receive text messages and photos. Talkray's API makes it possible for developers to add things like voice calling and text chats to their applications.
If you're developing mobile websites or native apps, you'd better take a closer look at the fine print. Some APIs, including one from Amazon, specifically exclude mobile applications. And there's not much explanation--or logic--behind the exclusions.