Savvy is an innovative voice-over-IP calling app using WebRTC. It was built with Xamarin Platform in C#, which allowed us to share about 80% of source code between the iOS and Android version.
In addition to the English version, Savvy was also localized in Spanish, Chinese, Korean, and Vietnamese.
The backend of Savvy featured API for user registration, billing, rate lookup, call routing, push notification, in-app purchase, as well as purchase with credit card. The communication layer was constructed with Prosody XMPP server, FreeSWITCH, and OpenSIPS.