We have a SIP paging server registered to an IP Office 9.0.3. the SIP server then sends the page to a multicast stream that is sent to a group of paging speakers (a mixture of Cyberdata and Algo devices). If we page from a digital phone (5410, 9504, or 9508) the audio is heard over the multicast stream on all speakers in the paging group. If we page from an H.323 phone (1616, 9611, or 9608) the audio is not heard through the multicast stream on our Cyberdata speakers in the paging group but is heard on the Algo paging horns in the same group. Does anyone have an idea of what to look for in the IP extension that would be causing the issue? The codec for the extensions and the SIP paging server are both G.711 u-law so it should be a codec issue.