Line 3 is lit up for no reason

[jungmann]

This morning we've noticed Line 3 on our IP Office 1416 phones has been lit up and no one is using it. No extension is lit up to indicate a phone off the hook or anything. Ideas on what would cause this? We can't get on it with any of the phones to try to hang it up. Not sure if this is an Avaya issue or our phone service provider issue.

[thiel2]

You've probably lost dial tone from the phone company on that line, thus the system has busied it out. Check the line where it connects to the control unit, and trace to the phone company's demarc. If no dial tone, contact the phone company for repair.