[asterisk-users] Asterisk as a distributed paging system

[Gordon Henderson]

On Wed, 22 Sep 2010, Matteo Fortini wrote:

> I'm building a paging system composed of roughly 10 switches in daisy
> chain, with an embedded box with a speaker and a microphone for each
> switch. The embedded box runs my software.
>
> I need the system to be resilient to any network partition, so that
> anyone can send announces from any mic to all the reachable clients. I'd
> need also to page a subset of all the speakers.
>
> I'm currently using some software I wrote which sends voice over
> multicast RTP and coordinates all the sites with multicast messages.
>
> I don't own the switches so each site will be assigned an address by
> DHCP, that's why I'm using multicast.
>
> I heard of asterisk and SIP as a possible alternative to my software,
> and I'd rather use tested and widely adopted software.
>
> Is there a way asterisk could be of use, or would I need to bend it too
> much?

It does this as standard.

However, to make it work you need to write some Asterisk dialplan code, 
and have SIP devices (phones) that can auto-answer and go into 
speakerphone mode.

It also doesn't use multicast, so the number of 'speakers' (phones) you 
have might be a limitation. I've tested it with 20 without any issues, 
however as it uses the internal conferernce facilities (meetme), I know 
that there are people out there using asterisk to host some very large 
conferernces, so I suspect for your implementation it won't be an issue...

Your requirement of any to all reachable, even if the network is broken is 
tricky - you might end up having an asterisk box at each switch (which I 
assume is an Ethernet switch) although then you'll have problems with the 
SIP device registrations.

Gordon