Session Border Controller and NAT

[imagemaster]

I have installed a SBC Service on a Linux machine. The issue is that the address that 3cx is putting in the config file is the local IP not the public IP; we are using NAT. How can I make sure that it broadcast the public IP so that remote phones know where to go to?

 

[Evolute IT]

The SBC is supposed to be local to the phones, so yes, it will put the private/local IP on the phones.

NAT doesn't matter, the SBC is an outbound tunnel connection.

 

[SteveITS]

Remote phones not in the network with the SBC need their own SBC, or they can be router phones which act as an SBC. The SBC does not go on the same network as the 3CX server.

 

[imagemaster]

I understand. If you plug a brand-new remote phone in, is there a way that it will get information like the SBC provides? That is a nice function.

 

[Evolute IT]

I understand. If you plug a brand-new remote phone in, is there a way that it will get information like the SBC provides? That is a nice function.

If you set it up prior to plug it in, yes. 3CX uses RPS to provide the config to phones on first boot.

 

[SteveITS]

@imagemaster The one trick is, update the firmware before connecting it. Some models seem to trigger the 3CX blacklist if the firmware is older.

 

[imagemaster]

I assume that the Allow 3cx to provision securely... has to be checked in the Phone->Options for v20? Is that correct?
Otherwise, how and where will the 3cx provide the information?

 

[SteveITS]

In general when a phone's MAC is added to 3CX it contacts the manufacturer, and when the phone connects (with 14 days) it asks the manufacturer's RPS to where it should connect.https://www.3cx.com/docs/manual/ip-phones/#h.5ownl22gt9re That points the phone to your 3CX server. The 3CX server will tell the phone what to do. This is all the default approach.

An SBC/router phone is used so phones from other networks can easily connect to the remote 3CX server.