For service providers implementing an endpoint VOIP Paging system (utilizing paging devices that employ multi-cast traffic) the gateway modem should be configured to disable "IGMP Snooping" if there are issues with some of their IP phones paging through a specific pager or pagers in their setup. In general this configuration setting can be accomplished on the Local Area Network (LAN) Setup page in the GUI of the gateway as follows:
The change should not require a reboot of the gateway and should take effect immediately.
Recheck for non-problematic paging operation for all phones on all switches. A leading symptom might be where internet phones connected up on one PoE switch tied to one of the LAN ports on the gateway does not have functional paging whereas IP phones on a similar switch tied to a different LAN port does have functional paging.