3CX On Prem: Firewall Issue

[greatchoice]

We have a customer that feels the need to lock down their firewall and only white list IPs for the ports we asked to open. What we are experiancing is an issue on on prem phones not being seen by the controller at all, not for PNP. They are on a VLAN but the ports are tagged and the IP Phone is on the same network as the controller.

We are unsure what may be causing the issue.

 

[Alphabetic]

The firewall out to the internet wont be causing this issue. Something on their network is blocking multicast which is why you cant see them in PnP. whats this controller you're talking about? is the 3CX on the same network as the phones.

 

[paulodagraca]

Hello greatchoice,

Often when the PNP does not work, this is caused by the Switch, where the Muilticast has been disabled.
You could request to check this on the voice VLAN that is in use, it should be set to enabled... just to be sure.

Paulo