Calls is a versatile communication application designed for Android users, enabling audio and video calling as well as messaging. The app supports various transport protocols such as UDP, TCP, and TLS, ensuring secure communication. It is compatible with multiple codecs including G711, G722, G729, GSM, iLBC, SPEEX, and OPUS, providing flexibility in voice quality and data usage. Key features include call transfer, recording capabilities, DTMF sending, and echo cancellation, making it suitable for personal and professional use.

The application integrates seamlessly with phone contacts, allowing for easy access and connectivity. Users can make calls over both 3G and Wi-Fi networks, enhancing accessibility regardless of internet conditions. Additionally, Calls supports push notifications and operates in the background, ensuring users never miss an important call. With the ability to manage multiple SIP accounts, this app is ideal for those who require a robust and efficient communication solution.