Phone Displays "Line In Use" Message

[kc27]

Several years ago, I connected my Ooma Telo to my house wiring, and connected my phone to a wall jack. This worked great for two or three years, then one day the dial tone was gone, and the phone displayed a "line in Use" message. As a test, I disconnected the phone from the wall jack, disconnected the Telo from the house wiring, and connected the phone directly into the Telo phone port. The "Line in Use" message was gone, and the phone operated correctly. From reading posts in these forums, the problem is likely that a component in the Telo has failed, and the solution is to get a replacement Telo.

Is Telo failure always the cause of this problem? There is only one phone on the house wiring, so the problem cannot be due to a phone being off the hook. I checked the Network Interface Box on the outside of the house and confirmed I am no longer connected to the incoming AT&T lines. Is there anything I should test before replacing this unit?

Thanks for any advice on this.

[murphy]

It is not the Telo. Are you certain there is nothing else connected to the house wiring?
Old ReplayTV, TiVo, heart monitor, telephone modem, clandestine phone in kid's bedroom, TV that displays incoming caller ID.

Is the phone you are using a modern phone or an ancient phone with real bells? If it's the latter it's time for a modern phone.

[kc27]

I got the ideas the Telo might be faulty after reading the comment below from another thread.

Phones that display "line in use" use the VOLTAGE on the line to determine when to display it. Old landline service provided 48 volts DC when the line was idle. PBX systems (and Ooma) provide about half that. When a phone on the line is off hook the voltage drops way down triggering the indicator.

If you are getting this indication when all phones are on hook, it indicates a bad phone or a bad Telo.

We only have one wired phone in the house. No modems, no medical equipment, etc.