Auto answer intercom?


My office has 6 employees, 5 telephone lines with Verizon fios. We have 3 buildings & things are a bit spread out. There has been a lot of time wasted looking for employees & I think an intercom would fix it.

I am interested in Asterisk & IP phones but was hoping to see if that would resolve my goal.

I would like to be able to hit an ‘intercom’ button, say “Hey Joe, where are you?”, then have the 6 IP phones (3 in one building, 2 in another, and 1 in the garage), all annouce my message, with the ability to have all 6 phones ‘listen’ so he could say, “I am in the garage” without picking up - if he is close enough. I would like it to not work on a phone that has an active call, and I would like it to shut down the other phones, if he were to pick up a line.

Can Asterisk do this? If so, what would be a good hardware recommendation for a new installation?


You will need SIP phones that can be forced in to handsfree mode. Often this can be used by a suitable AddHeader call in the dialplan.

The announcement part of this can be done using the Page application. I’m not in a position to check (run core show application page) whether that has an option to put the called phones into two way mode. Normally they are put in to listen only mode. If they can be put into two way mode, everyone will here everyone else, and the responder will need to be close enough to the phone to trigger its VOX.

Since I am new to this, do you have a recommended vendor I should be using? I have no equipment at all & can use just about anything at this point.

I do want all IP phones to be forced into speakerphone mode - unless someone is on their phone, then the page should ignore it.

Can I make a page group with the entire group of phones in the system? I would like it to be a full duplex setup until someone picks up their headset, then the other phones in the page should be gone.

Again I dont want a page beep, I do want a verbal announcement.


Nothing in the SIP protocol would signal the transition from handsfree to handset modes.

The page application sets up a call to all the phones and then dumps them into a conference where the initiator is the only one that an speak. It is intended for real time speech pages.

[quote]centosCLI> core show application page
-= Info about application ‘Page’ =-

Pages phones

Places outbound calls to the given technology / resource and dumps
them into a conference bridge as muted participants. The original
caller is dumped into the conference as a speaker and the room is
destroyed when the original caller leaves. Valid options are:
d - full duplex audio
q - quiet, do not play beep to caller
r - record the page into a file (see ‘r’ for app_meetme)
s - only dial channel if devicestate says it is not in use[/quote]

So is there a way to have the page/conference a two way conversation vs the initiator being the only one to speak? Or do I just choose option D which would give me the two way speech?

Would the page/conference interrupt someone who is using the phone?

d should put everyone full duplex. The problem would be to put just one person full duplex.

The call is a normal call, so will either hit busy or ring on the second line on the phone. The s option is to prevent it ringing on the second line. You probably need to turn on call counting for s to work.