The Punch app is a messenger you can still use even when your phone is locked. Currently in Beta, the iPhone app is described as a "lock screen walkie-talkie."
The lock screen app makes it easier to converse with your friends and family, especially with the group chat feature. You can send audio messages directly, which are converted to text if your smartphone is on silent. The Punch app also focuses on security by deleting the messages from their servers as soon as they are sent. It is safe for drivers, as the handsfree Drive Mode feature will automatically play video and audio and read notifications out loud. Custom lock screen wallpapers are also shown, which display the weather with a changing photo background.