How does Standby mode work?
Users place themselves manually in Standby mode when they change their status to Offline or exit Zello. Users are automatically placed in Standby mode when they are not connected to the Internet or their phone is off.
While users are in Standby mode, their individual contacts can send them messages. In order to receive the messages, the user must sign in within 7 days after a message was sent. Messages will be played when users come back online in the order that they were received. If push notifications are enabled, the user will see a notification when they are receiving messages, as long as they did not change their status to Offline. Note that push notifications need an internet connection to be delivered.
Channel voice messages and channel photos are not received while users are in Standby mode. Channel alerts will be sent as push notifications to users in Standby mode, if the sender has chosen to alert all channel members.
The only reason for a user to be displayed as offline, instead of Standby, is that the user has never signed in.