Make It So Only Called Number Can Disconnect Call

I don’t know if I’ve found this anywhere, though I could be using incorrect search terms. Anyway, with our current Alcatel phone system, we have it set so if a caller calls 911, only 911 can disconnect the call - to avoid the caller hanging up with 911 if it was an accident. If a caller calls 911 and tries to hang up after the call has been answered, the phone will keep ringing on the caller’s end and a message, “we are trying to reconnect the call. please hold on,” is played which dispatchers can hear.

Is it possible to do that with FreePBX, either through the GUI or command line? I do still want the caller to be able to hang up if they accidentally dial and it’s early enough that the call has not been routed through to 911 yet. (There is currently a short announcement played to the caller telling them that they have dialed 911 and to remain on the line - after that announcement, the call is routed through to the PSAP).


Probably not, in the good old days of ‘landlines’ the PSAP would ‘line grab’ the call with coordination of the ‘phone company’ , such coordination is not feasible with SIP, BUT, if the call is in anyway completed, and the caller hangs up, it is YOUR responsibility that the PSAP can return the call to exactly the same device that initiated the call, if that fails , it must be routed to ‘wet ware’ that can ‘check and verify’, failure to be able to do that can cause the big red car to roll and you get a sizeable bill. With new laws, then your liability is increased as can be the penalties. I suggest you as a first step have the caller keep on the line and apologize on answer to ameliorate the situation.

It’s only fully possible on analogue lines, and even then I don’t think that chan_dahdi supports it. It requires a distinction between Hangup and Release, and preferably, as is the case for analogue lines, that the FXS only be able to do a Hangup and not, also, a Release.

SIP doesn’t have the distinction, so BYE will always end the call for the station issuing the BYE.

If such a feature exists, it would have to be with the device, not the PBX. I have a vague memory from a very long time ago that there is something like this in cisco spa devices.

A line that has been ‘grabbed’ behave differently from a loop start line (or for that matter a ground start) , It will not respond to hangups or flashes or blinks, anything connected to it will always see an extant current loop on going ‘off hook’ (i.e. low impedance) locally and although it could be arranged at the Dahdi level, it would need to be responded to from that dahdi driver. It’s been about 237 years since I needed to deal with it , but memory prompts me that the Sangoma hardware with it’s wanpipe driver was better built to handle such a situation, just monitor it in hi-impedence mode (much like it’s ‘lline-tap’ mode) to see if there is anything still there and so respond, truth is that it is such an edge case we should probably just move on. because almost nobody has a physical ‘copper loop’ circuit from the CO anymore :wink:

How is this being done and are you in the US? Because if you are in the latter then calls to 911 must be routed directly to the PSAP. This means answering the call or routing it to some place within the PBX before the PSAP is against the 911 laws.

You could play this recording as early media where the channel is not answered while it is played back and still directly routes to the PSAP.

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Also hanging up on the PSAP after they answer can trigger a check by the police. So they shouldnt be surprised if after they hang up on 911 the po-po knock on their door.

They never treat hangups as a fat fingered call. They answer, you hangup could mean you didnt want to be caught calling 911 or have them found on an open line.

And that so routed call MUST carry information as to how the PSAP can successfully call it back and get a sentient human.

Yup and the preference is the original caller but the site emergency contact is also good. Generally the same contact that got the alert notice.

And the ‘site emergency contact’ should be pre-aware of who made the call, That is your responsibility/Liability.

I’ll preface with this: my background isn’t in phones, but I came into this position after a temporary internship ended. I have been working to familiarize myself with everything I can. As we look into switching to FreePBX I’ve been finding this a good opportunity for me to learn the ins and outs of a PBX from the ground up!

That said, looking at the 911 call logs through our Alcatel interface it seems like the announcement is basically early media, and then it’s directly routed to the PSAP immediately following the announcement.

(12:28:05 PM is the message, which is about 5 seconds long, 12:28:10 PM is when the call is actually routed out - also note that we can reach 911 multiple ways - dialing 911, 9911, or 91911, despite what the #91911 shows)

Each phone (we don’t utilize softphones) that calls 911 has its direct number sent to the PSAP, or the main school telephone number. With each 911 call that makes it to the point of being routed to the PSAP there are on- and off-site emergency contacts who:

-get a live listen-only phone call of the conversation between the caller and dispatcher
-an email saying there was a 911 call and who called, their extension, and address
-a pop up notification and alert tone on their computer giving that same information, as well as a facility map

We definitely do educate teachers and other staff to stay on the line if they accidentally call 911. Most of them do so, but some will not. Also on occasion a student will get a hold of the phone and dial 911. My hope is that students are being educated how to properly use 911 and what to do if they mistakenly dial it.

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