Meraki Port Isolation and 3cx system

[bllawrence]

One of our companies has multiple locations, using a single 3cx system hosted by 3cx. Each site has its own local SBC. We would like to turn on port isolation on the Meraki switches that we are using but when we do that, we lose the ability to transfer calls from one extension to another. the initial call can be connected, but we are unable to transfer calls. Has anyone run into this issue and found a fix for it?

 

[SteveITS]

In each extension's Options there is a checkbox "PBX Delivers Audio" to force audio streams through the 3CX server. Normally for calls within the same LAN audio doesn't get past the SBC. Depending on the number of extensions at each location and the number of calls it might impact bandwidth used and server resources.

 

[cobaltit]

Unable to transfer calls or have no audio after transfer? Unable to transfer indicates a SIP issue, no audio after transfer would be a RTP issue. For the first one, PBX delivers audio isn't going to do anything.

Regardless, I don't see how port isolation is going to work in any scenario. What exactly are you trying to achieve with port isolation?

 

[bllawrence]

Thanks for the replies SteveITS and cobaltit. The issue, as I'm getting more information, was that when they transferred the call, the phone would ring but there was no audio path. The reasoning for the port isolation is just more security (no direct communication) between workstations. Email, shared files and such are handled through servers so the port isolation does not affect that type of communication. Of course we have the workstations connected via the pc port on the phones.

 

[Evolute IT]

Port isolation will cause more trouble than security in your case. If you need more security, use port security, VLANs, good routing and such.

PBX Delivers Audio might help, but shouldn't be the go-to solution.

 

[bllawrence]

For more clarification, turning on the option for PBX delivers audio, would cause all audio to constantly flow through the PBX instead of the normal SIP endpoint to endpoint audio flow, right? Does having an SBC at each location make a difference in this? Or is the SBC pretty much just for provisioning?

 

[bllawrence]

Port isolation will cause more trouble than security in your case. If you need more security, use port security, VLANs, good routing and such.

PBX Delivers Audio might help, but shouldn't be the go-to solution.

Thanks for your response. we are already using vlans to separate voice from data.

 

[Evolute IT]

For more clarification, turning on the option for PBX delivers audio, would cause all audio to constantly flow through the PBX instead of the normal SIP endpoint to endpoint audio flow, right? Does having an SBC at each location make a difference in this? Or is the SBC pretty much just for provisioning?

Yes that's what it does. When using SBCs, the call audio is usually routed locally since phones should be able to talk to each other in the same network. However, in some cases, it is necessary to enable the PBX Delivers Audio to make sure that everything is always routed back and forth.