sundance-communications.com/forum Forums TDM Business Telephone Systems Nortel Telephones & Systems Compact ICS Intermittent problem receiving and making calls

Here some info:
https://en.wikipedia.org/wiki/Tip_and_ring

"I have only see cards go bad in a system like this once, but the unit was struck by lightning (at a different location). I was leaning towards a possible bad trunk card, but didn't know if this is a common thing or not.'

Sorry, which unit was hit by lightening?

It should be easy enough to just change the trunk card to see what happens. If it makes no difference, the card now in your hand, is fine!
I have had trunk cards lose one port - usually stops ringing at all. Probably due to lightening/power spikes.

If only a couple of lines in use, you could swap lines & reprogram. But since you have 4 lines in use, that option isn't available.

This particular unit wasn't hit by lightning. When I had stopped by this location, the problem wasn't happening, so I gave them some troubleshooting options and told them to get back to me. Haven't heard back in a week. I do have one new spare trunk card to try.

One thing that I did remember about this location is they put a phone plate on steel I beam, and fabricated a small metal plate. When we first put the phone it, it did not work, because the back of plastic phone jack was shorting out against the metal. We then put a piece of cardboard in between the jack and metal. Not sure if this was shorting out again would cause any issues with the trunk lines.