Star Call is a free Android application developed by Starcall Communications in the category of Social & Communication. The app offers VoIP calls and SMSs over Wifi, 3G/4G, edge, or UMTS. It also provides cross-platform instant messaging, enabling Android users to chat with iPhone users or Windows OS users to chat with BlackBerry users. With unlimited mobile chatting, the app increases the stickiness to your brand.

The app's sign-up process is incredibly easy, as it only requires your mobile number as a user ID. Once you sign up, the app automatically creates a buddy list, and it gives you the facility to invite phonebook contacts to install the app. Moreover, it enables mobile top-up, which is an excellent feature for users who want to recharge their mobile balance without leaving the app.

Overall, Star Call is an excellent app that fulfills all your communication needs with its easy sign-up process, cross-platform instant messaging, and mobile top-up feature.