Zello utilizes circular buffer to locally store history on devices. In practice, this mean  the oldest stored messages will be deleted to make room for newer messages once the storage limit has been reached. 

Maximum storage is determined by either the end-user from their in-app settings, or by an admin from the management console's Settings page (operating system > local device history). 

If a value isn't configured by the admin or user, Zello will default to the following storage limits: 

• 32 Mb for Android 
• 32 Mb for iOS
• 64 Mb for PC 

Deleted messages cannot be restored.