Right. That is why I was asking how the Page Pro module implements it.
Nothing in the listing even mentions Multicast: https://www.freepbx.org/paging-pro/
The wiki article does: https://wiki.freepbx.org/display/FPG/Page+Pro-Admin+Guide
If I set up a page group in page pro using a multicast address, is that generated from the PBX?
Because, as I may not have clearly stated in my OP, I want a singel page group that pages both some extensions like normal (connected to Snom PA1) and also to multicast to a bunch of phones at a building with no overhead speakers.
Based on the above links, I am 100% certain Page Pro fits my need if the PBX was on site, on the LAN.
I can easily make buttons on the desk phones for multicast directly. But then I don’t get the page out to the overhead speakers on the Snom in the other building that is not on the same network.
Yes, I could put up a routed IPSEC VPN tunnel between the two sites to handle the multicast directly as Snom units can receive it. But I have no need for a VPN now, and do not want to introduce complexity on the network for no reason. That is why I am asking the question.