Voice Lock: Speak to Unlock is a free Android app developed by SM Infotech that allows users to lock and unlock their mobile screen using voice recognition technology. The app also provides users with the option to set a PIN or pattern lock as an alternative to voice recognition. Additionally, users can set a security question and answer in case they forget their lock.

Voice Lock: Speak to Unlock also offers the option to set a fake icon for the app, as well as a custom theme with a picture or photo on the lock screen. Users can also enable or disable the unlock sound and vibrate, even when the phone is unlocked. The app requires two permissions, including recorded audio to access the user's voice and a system alert window to start overlays on other apps.

Overall, Voice Lock: Speak to Unlock provides a unique and innovative way to secure your mobile device, and its additional features make it a versatile and customizable option for users.