PSTN Line Failure

What does PSTN FAIL mean?

The Public Switched Telephone Network (PSTN) line is not functioning correctly. This condition is indicated when the line voltage is less than 33 VDC, the telephone line is physically missing, or no dial tone is detected. This fault prevents the emergency phone system from establishing outgoing calls via the landline network.

• The physical telephone line connection to the phone board is disconnected or faulty.
• The PSTN line voltage supplied to the phone board is below the operational threshold of 33 VDC.
• There is an absence of a dial tone on the PSTN line, indicating an issue with the telephone service itself.

Click steps to track your progress.

1. 1

   Verify the telephone line is securely connected to the PSTN input terminals on the phone board.

2. 2

   Measure the DC voltage across the PSTN input terminals on the phone board; confirm it is greater than or equal to 33 VDC.

3. 3

   Connect a known working analog telephone to the PSTN line and listen for a clear dial tone.