Paging, in a nutshell, a basic communication mechanism to announce to a group without really calling each one of them. We see the power of paging in an airport when they announce the boarding, departure or arrival information of a flight or in a hospital when they announce for a nurse, etc. So paging is a very useful tool to have in any PBX. There are couple of ways to perform paging – Unicast and Multicast.
It is a common knowledge that snomONE supports both unicast and the multicast paging methods. In the SIP world, the Unicast paging is achieved by sending a SIP INVITE to each of the phone with an auto-answer request. This works great regardless of whether the phones are on the same network as the snomONE. But when it comes to multicast paging, it is desirable that both the phones and the snomONE be on the same network. The main reason for this is that it is an herculean task(almost impossible) to get the multicast working over the internet. So, the multicast paging is pretty much limited to CPE installations. For the hosted snomONE installations you have to rely, mostly, on the Unicast paging.
Even though the Unicast paging is a good solution for both CPE and hosted implementations, it has some downside to it. They are – possible setup delay and CPU load. Because snomONE has to send SIP INVITE to each of the paging members and it can take few extra seconds(setup delay) if the group is really BIG. Also, the RTP streams have to be setup for each of these phones from snomONE (CPU load). So you really wish if there is a multicast paging solution that works regardless of the network structure.
As we know, there is a solution for every problem. The same goes true for multicast paging on a hosted installations too. With the snomONE-mini based paging manager (well, not an official name :-)), you can really have the multicast paging for the hosted snomONEs.
The overall setup is really simple.
- Provision the remote phones with the multicast paging group address as usual.
- Throw in a snomONE mini at the customer premise.
- Register a trunk from snomONE mini to a hosted extension.
- Create a multicast paging account on snomONE mini matching the registration trunk account and the same multicast address as the one on the hosted system.
- Now pickup any phone on the customer site and dial the multicast paging account on the snomONE mini. You should hear the paging on all the phones that are provisioned on the first bullet.
That’s it for the setup. Yes, it is that simple!