[VoiceOps] False 911 calls and old abandoned DID
bsvec at teamonesolutions.com
Thu Jan 21 18:25:16 EST 2021
Thanks for sharing. 25+ years, most of which was hands on in the field with analog lines, PBX, low voltage cable, etc. and I never came across or heard of this happening. I fully understand how it is technically possible ( I have even demonstrated pulse dialing with a key on a 66 block with a butt set), but it also seems just as likely for *any* number to be dialed as it does for 911 so I am still not 100% convinced, but am open to knowing more. Certainly 0 for the operator being 10 pulses should happen at least as often if not more than 911 since it would just need 10 correct pulses and no perfectly placed longer pauses twice after the first 9 digits which seems would be much more rare.
You wrote, "I audited some more. One of them, with a butt set in monitor mode, I heard a lot static with, "If you'd like to make a call please hang up and try again," in the background. Looking at our logs, that one had called 911 too. We keep those logs for 6 months. In that 6 month period, my analysis found 16 "left-in" stations that had presumably self-dialed 911 a total of 35 times.”
How do you explain the intercept message in the background of a call dialing 911? That sounds to me like the result of a double punched line or crosstalk.
Maybe living and working in N. California with the fair weather explains my lack of experience around this. I am aware that many parts of the country do a lot of extra things to protect against lightning strikes that are unusual to see in N. California. What I have seen a lot of is misconfigured or compromised PBX and voicemail systems call 911 and also plenty of user error on centrex or PBX lines that require 9. DTMF or pulse it is pretty easy to dial 911 by accident and a lot of people are afraid or embarrassed to admit they may have done it.
Do you care to share what make/model of equipment was alerting you to the "MORE THAN 10 DIAL PULSES WERE RECEIVED” message? Just curious to learn more.
> On Jan 21, 2021, at 3:07 PM, Mike Johnston <mjohnston at wiktel.com> wrote:
> Some of my equipment will show a notice, hinting at a possible issue, when "MORE THAN 10 DIAL PULSES WERE RECEIVED". A couple years ago, the responsibility of our switching gear was being transitioned to me as the previous guy was retiring. During that period of time, I noticed a station in particular would throw that message a lot, up to 50 times a day.
> There is also an entry every time somebody calls 911.
> One late night I saw somebody call 911 multiple times. I looked up the line and found it was the one with all the MORE THAN 10 DIAL PULSES WERE RECEIVED issues. I called the sheriff's office. I asked if they had any weird 911 calls from that number. They replied, ecstatically, "YES, like seven times!" They said it would be static for a long period of time and eventually hang up. I suppose the dispatchers really shouldn't be quick to hang up their end, just in case. So they have to wait out the call...listening to the static.
> I promptly unwired it and put in a trouble. I thought, surely this isn't a common issue, right? Lines with static on them don't just call 911 by themselves! Do they? Well, in my phone call with the Sheriff's Office, they said this is NOT an out of the ordinary event for them.
> I audited some more. One of them, with a butt set in monitor mode, I heard a lot static with, "If you'd like to make a call please hang up and try again," in the background. Looking at our logs, that one had called 911 too. We keep those logs for 6 months. In that 6 month period, my analysis found 16 "left-in" stations that had presumably self-dialed 911 a total of 35 times.
> Since I stumbled across that, we keep a much closer eye on these sorts of things. Basically, any line that frequently or repeatably throws the MORE THAN 10 DIAL PULSES WERE RECEIVED notice, we do an audit on.
> A little more background on what causes this:
> Pulse dialing is performed by rapidly interrupting the telephone circuit for each digit dialed. This method was sometimes referred to as loop disconnect dialing. When you think of pulse dialing, you might immediately think of rotary phones. You might also have visions of stepping switches.
> One interrupt represents the digit "1" being dialed. Two rapid interrupts represents the digit "2", and so on. You need to have at least a brief timeout between the digits to indicate you are done with that digit and starting the next. The exact timing is relatively loose, leaving a lot of wiggle room. Any sort of interference that is creating a make/break cycle has the potential to pulse dial. Multiple makes and breaks with the right timing (and again, the timing is pretty loose) could conceivably call anywhere...with no human being involved! The odd thing isn't having it happen - it's having it happen to a specific number.
> For 911, you simply need:
> - 9 rapid interruptions
> - pause
> - 1 interruption
> - pause
> - 1 interruption
> For lines that are shorting out, arcing, in water, or whatever, it is only a matter of time.
> -Mike Johnston
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