You can receive this message because of a variety of things:

• The Panel lost power for an extended period and the panel battery is drained, therefore the cellular unit cannot transmit.
• The cell unit in the alarm panel has been tampered with, destroyed, disconnected or has otherwise malfunctioned.

*Check the following above, if all checks out ok contact CPI Technical Support at 1.800.948.7133 for further troubleshooting or schedule a service visit.