The main network is short of IPs, so we created a VLAN and moved all VoIP phones to this new VLAN. The PBX has to remain in the main network. We setup firewall rules to allow all traffic between the main network and the VLAN on both directions. All the VoIP phones on this VLAN work fine EXCEPT that
1. Paging voice do not come out from the speakers on all phones any more
2. Background music do not come out from the speakers on all phones any more.
For troubleshooting purpose, we moved a VoIP phone back to the main network, the above 2 problems disappeared right away, the phone worked as normal again.
I could be wrong, but I think we need to enable broadcast between the main network and the VLAN on the firewall. But i have no idea how to do it.
The firewall is SonicWALL TZ215