Checking for Messages
Your device listens for new messages at regular listen intervals. Satellites announce recently sent messages, and your device receives the message at the next listen interval. The device will listen for 10 minutes after you send a message, and then again every hour.
You can force a check for messages by manually checking for messages, sending a message, or sending a track point. During a check, your device connects to satellites and receives messages waiting to be sent to your device.