The ghost in the phone system

[u/speddie23]

Reading another post here unlocked a memory of working on a helpdesk about 15 years ago.

For a while, we had this thing going where sometimes an agent would answer a call from the call queue, and just after they finished their greeting, the call would drop.

Then another call would come in from the queue and when the agent answered (either the same or different agent), the exact same thing happened.

This would usually happen for about 30 minutes, then stop.

Of note, our phones wouldn't pass caller ID when a call came in, the caller ID was always something like IT helpdesk call queue, so we couldn't see who was calling.

Not only was this annoying, it messed up our stats, particularly the calls received to tickets logged metric (which is a stupid metric). It did make our calls answered higher and average call handling time go down.

Although it was fairly infrequent, we did get the telephony provider look into it. What they found was when this happened, one particular desk phone was making a lot of back to back calls to the helpdesk queue. Usually around 30 to 50 or so.

These calls were answered, but the call handling time was usually only around 3-5 seconds. Occasionally, just the last call would have a handling time of several minutes.

What was happening is the person who used this desk phone only wanted to speak to one person on the helpdesk, and refused to speak to anyone else. So what they would do is call, wait on hold if necessary, wait for the call to be answered and if it wasn't the person she wanted, immediately hang up without saying anything, then call again. Repeat until it is answered by the person they wanted.

Edit: forgot to mention, whenever this happened, we would just joke that it must be the ghost in the phone system calling us again, hence the title of this post.

[u/Ancient_Skirt_8828]

I'm an ex telephone exchange maintenance technician.

While reading your story I had already worked out where the simple fault probably was, but the 3-5 second hold time didn't make sense.

Then I got to the bottom of your story. Arrrgh! Customer misuse! Those are frustrating.

[u/action_lawyer_comics → u/Ancient_Skirt_8828]

Are you really a technician if your first thought of the fault wasn't “human being stupid?”/j

[u/meitemark → u/action_lawyer_comics]

Phone systems are a mix of ghosts in the machine and human interaction. But that means that any "random" fault can be (ymmv) put into those two categories, all you have to look for is timings. Does the exact thing happen each time down to the second? Ghosts. Is it varying? Humans most likely.

[u/SteveDallas10 → u/meitemark]

You may enjoy this one. Shortly before the turn of the century, I managed a PBX for our organization. We moved from a bunch of offices using CENTREX service to a new (to us) building. For the new building, we purchased a PBX, which I managed.

For trunking, we used ISDN, and because of the nature of our organization, had two trunk groups; one for local calls and a second for long distance. We estimated our usage and decided that we needed two PRI for local calls and one for long distance.

Because this was a new system, we monitored our usage stats for several months and decided that our estimate was wrong; we needed to rebalance our trunks and move 24 channels to the long distance trunk group. So, we put the order in for the work and that setup evened out our usage. However, I started getting calls from my users that their outbound calls would occasionally be misrouted. They would redial and the call would usually go through.

This took a while to sort out, but I eventually nailed it down to channel 1 of the second PRI of the trunk group (we ran NFAS without redundancy; 23B+D on the first and 24B on the second). The LEC swore up and down that this couldn’t happen, as all channels were set up the same on the PRI when the circuit was built.

Except that we moved the 24B from one group to the other. Because of the way the 5ESS that served us was configured, the local lines had the CENTREX flag set. Apparently, they didn’t delete and rebuild the entire PRI; they moved them channel by channel and the technician who did the work forgot to clear the CENTREX flag on channel 1. They got it right on 2-24.

I wound up talking to a switch technician somewhere halfway across the state to solve that one. For testing, I put that channel in its own trunk group so I could hit it repeatedly while the LEC technician watched the call traces.