Background ringing and Automatic Calls

[GarenCAnderson]

Good afternoon everyone.
I've got a difficult one that I've been working on for about a month now and I've made almost no progress.

I have a group of 6 digital phones. It's a mix of 2616's and 3904's.
They are set up so that when one person answers a call, anyone else on this bank of phones can pick up their handset and listen in or comment on whats going on.
This has been operating flawlessly for over three years now with this configuration.

My site upgraded to 7.5 about a month ago. The end user tells me that the issue started at the time of the upgrade. Considering how my I trust my user base, I can't confirm this as fact. Regardless, moving on.

The issue is that when someone in this group is on the telephone, you can hear noise in the background. Not quite full volume but pretty close to it. You can hear dial tone, DTMF tones, or the ringing cadence like you called someone and are waiting for them to pick up. It only lasts a moment before going away. It might come back and happen a few times per call, or it might not happen at all.
It seems very sporadic and intermittenet, but it's always on one of these 6 telephones. Additionally, it seems to only happen when there is someone listening in on the telephone call, but I have heard rumors that sometimes it happens when no one is listening.
The caller at the other end DOES hear the sound, and considering the nature of this call center, having someone hear dial tone and think you hung up on them could put lives in danger.

Also, last night I received reports that phones from this site are calling my other site in portland on their own. There are auto dial keys on the telephones so I can see there being a connection between the two, but can't quite tie it down. Also, other telephones on the facility are supposedly calling this group of 6 phones on their own. These last two symptoms were only listed last night so it might be something else completed unrelated.

As for troubleshooting, I have replaced the line card which all of these phones are on and placed them on a different card just in case the card slot was bad, I've also reprogrammed the phones (I'll post programming when I get to the office.).

Any help that can be offered or suggestions would be greatly appreciated.

Thanks in advance to this AMAZING community.

 

[KCFLHRC]

That is s strange one. I think looking at the firmware on the 3904 phones would be a good starting point. There is no firmware on 2616's so that's not an option. I have also seen stuck buttons on phones cause very strange things.

 

[GarenCAnderson]

I had updated the firmware on the telephones last week. So I'm pretty sure that I can rule that out.

The autodialing out and the calls from around the site symptoms have been resolved. They were associated with a different issue and I've removed them from the equation.

So, I'm back to just hearing dial tone, ringing, and DTMF tones in the background of my phone calls with this site.
I was able to rule out the conference cards as having any influence on the issue as they issue remained with both conference cards disabled.
Additionally, the problem is present when making Internal > Internal calls, Internal > External, and External > Internal calls.

Again, any iformation or suggestions that can be offered would be greatly appreciated.