Barix IP Audio devices are an excellent solution when it comes to special SIP interfacing applications. Being it an audio monitoring application, where a call should be placed if a microphone picks up sounds above a certain threshold, or a SIP door station – the standard SIP application, which can be loaded on all Annuncicom and Exstreamer devices, serves well.
But do you know that you can also use a Barix device as a SIP gateway to traditional, multizone paging systems ?
How do you then select a zone ?
The SIP firmware can control local relays on the device, if existing (Exstreamer 500, for example, offers 4 relays). These can be commanded in the SIP call by means of standard signalling (SIP Info and RFC2833). Many IP PBX’es also allow you to send specific commands when you initiate a call, this is the perfect time to select a zone automatically.
The Barix wiki contains a nice article describing the exact configuration necessary of an Asterisk instance to offer the luxury of direct zone selection by extension. If done this way, a user of the phone system can just dial one of a selection of extensions, and the Barix SIP Gateway (actually, an Exstreamer 500 or Annuncicom 1000 device) will select the specific zone(s) to page to automatically, based on the actual extension called.
Here is a link to the general overview of how this is done: SIP Paging
And here is the article detailing the bits and pieces on how to configure Asterisk to directly control the relays from SIP