So I setup a page group (3333) to match up to a multicast paging group and then programmed each Grandstream to listen on that same port. When I press the blf for 3333 there is no multicast paging audio but if I setup a multicast paging button on the phone with the port I programmed for them to listen on then it works great. Am I missing something in the setup?
I have the same problem. I can page fine from my Cisco SPA phones, but when using the extension setup using Paging Pro, I get no multicast traffic coming from the server.
Found my problem. Our system has two network interfaces and I was missing a route for the multicast traffic.
MDIT - Where did you make the change? From with FreePBX or on your L3 devices?