Symptoms:
Facts:
Causes: Most vendor switches have IGMP enabled by default which means that any Multicast traffic will not be forwarded unless there is a request for that particular Multicast address.
WAN routers not properly configured for IGMP and Multicast Routing Protocol
LAN switches are blocking paging when booted in IP mode. To prove or disprove this, piggy back one NBX phone to another (plug the ethernet connection from one to feed off of another), and issue a page from either of the piggy backed phones. If paging is heard on the piggy backed phone, but not others, this proves paging is being blocked in the switches - IGMP config.
Fixes: The following are required for to support Paging, Conference, BLF lamps, Mapped POTS Lines, and Date and Time Display updates on remote IP phones, and in some cases even on the network LOCAL to the NBX when the NBX is operating in IP or IP-On-The-Fly mode:
1. A Physical gateway (router) on same subnet must exist and be operational.
2. NCP's network configs must be correct (IP address, subnet mask, and gateway)
3. IGMP and Multicast Routing Protocol must be configured and enabled throughout the connection for remote IP phones (all routers and layer 3 switches must support IGMP)
4. Switches must have IGMP enabled, but NOT be enabled for snooping/learning/filtering/pruning
NBX uses the system gateway (router) to send Paging packets, even on the same network if IP is enabled. This is unlike regular NBX phone calls, which always attempt to use layer 2 on the same subnet, even if the system is running in IP mode. A valid gateway must exist, and the NBX's IP settings must all be correct and non-conflicting for the network on which the NBX is running.
If you can reboot the system in Ethernet mode and your paging problem is resolved, you have a gateway or network configuration issue.
Anomalies:
These are known limitations
— David Gonzalez 2021/04/12 09:20