Paging and Intercom: Force if Busy


So I’m setting up a system whereby if there is an emergency (tornado, flood, fire, etc) someone can pick up the phone and page a set of VoIP speakers (made by CyberData). However, when I check the “Force if Busy” box in the “Paging and Intercom” section, nothing happens. If someone else is using that speaker to page, and I have an emergency and dial that paging group, that speaker doesn’t get the message.

I have also tried it on a snom phone and the same thing happens. If someone is on the phone, and I try to do an emergency page, the call is never interrupted.

Any ideas?


You might be SOL on this one. Normally you are paging a phone which also has a speaker phone. So when you are paging a phone the page goes to the speaker phone part, the force page option just says to include or not include the phone if the line is busy. With a dedicated speaker phone device it’s already using the speaker phone portion so does not have another source to send the audio to.

Which is what happens here if we are using a phone as a speaker phone when somebody attempts to page you it will not happen because the speaker phone portion is already busy.

I’d ask the manufacture about it, it might the case and/or a special code might need to be sent to the phone first.

As eluded to, “Force if Busy” just tells Asterisk to send the call to that phone whether or not it sees the channel as busy. Otherwise, it doesn’t even try. It’s equipment dependent and there may be some equipment that can be configured different ways.

If there is some sort of different alert info or something that could be included in the sip header, then you could probably write a custom macro to address the issue on that device and there are hooks already designed into paging that would let you take advantage of such.

Thanks guys!

Is there any way to kick someone off a channel? I guess the next best thing is to break the connection and then page it?

I can’t go messing with paging here but in asterisk there is the CLI command soft hangup which can hang up a existing call. So you should be able to do it.

I found an asterisk command in voip-info for extenspy, but when I try to extenspy an extension with the whisper option, only the party that is talking to the extension can hear me.

IE: A calls B, call is connected. C does an Extenspy(B, whisper) and can hear the conversation between A and B, but only A can hear what C says.

Ideas on this? This is getting closer to what I would like to do.


I am curious. Just how long are the conversations on your paging system? If it is a paging system, you should be able to hear if it is in use and most of the ones I have been around, the pages are fairly short with long intervals between pages.

Sorry if I am sounding like a smart ass. I just don’t understand the need for this.

The fact of the matter is that it’s for emergencies. Will the emergency page occur while someone else is paging or on the phone? Probably not, but if it’s an emergency and the on-site physician/paramedic/bomb-diffuser was on the phone at the time of the page, that might be an issue because “time is of the essence”

I’m also thinking of locations like schools where they have announcements that tend to be lengthy - minutes long.

So you don’t sound like smartass, it’s actually a good question!

there’s something important to think about if you are going to try and implement something like this. You don’t want to barge into the paging system if the person who is currently using it is addressing the same or a different emergency… keep that in mind.

I’ve already thought about that, but what other options are there?

If 5 people call 911 for the same reason, do they send 5 ambulances to the same location?

Assuming the likelihood of a non-emergency page being interrupted is low, interrupting an emergency page with another emergency page would be even lower. Especially since the emergency page itself will be short and to-the-point. “Dr. XXX emergency in room YYY”

Anyhow, I’d like to know if extenspy is not working for a reason.

the concept is the same as with schemes that allow lines to be barged in for 911. You allow it, as long as the line you are calling into is not already a 911 call. So you want to do the same thing in a scenario like this - make it so an emergency page can not barge into and existing emergency page.

If you have ever been to a 911 center or worked in one. You’ll know that they are smarter then that and actually prefer that they get 5 calls instead of 1, it confirms that it’s real and when the details all match it helps in dispatching.

you are mis-understand I think. My point is, if you have a PBX with a single phone line for instance, and someone calls 911 and is talking to the PSAT. Someone else on your PBX in the other room picks up the phone to call 911. You don’t want to cut off the first call that is already in contact. If that call is not with 911, then you allow it to be cut off.

So my point in this case, if someone pages the ‘emergency page’ number, you don’t want someone else to break in and disrupt the page in progress thus garbling the page. (Not as big of a deal since both can probably hear the page, but if you are going to do the extra work for all this, you may as well take everything into consideration.)

yes you are correct. But at the same time very few businesses have only 1 phone line. (Homes that’s a different matter).

I have the same logic here. In case of an emergency we always use the analog line as the primary outbound for 911 calls, we also have a PRI but if there is a problem in the building it is possibe that the equipment that services that could be compromised so we use the single outbound analog line we have first when dialing 911, if that is busy with a 911 call then next call to 911 will attempt to use the PRI.

We learned that lesson the hard way here two years ago. The service for the PRI and our internet (different carrier) comes into the building differently then the good old POTS line. The restaurant had a small grease fire and the carrier room backs up to that wall (yes dumb location) but somehow the power was cut and it tripped the emergency shutdown for that room and we lost the PRI. Our office had power along with some smoke but we could not call out on the phones.

It’s great that my requirement has sparked this discussion, but the point of discussing it is moot if I can’t get it to work in the first place.

I’m still thinking ExtenSpy is my best bet so far. It also allows the caller to hear the existing conversation, thereby satisfying the requirement that another emergency page not be disconnected. All I need now is for the correct channel to be able to get the audio feed.