Changing Public IP with Dual NIC

[Dutchigander]

Hey folks,

We currently have 3CX V16 installed on a virtual Windows server with AT&T SIP trunks. The trunks are direct, so the server has two NICs, one for internet access and one for the trunks. During initial setup I set the public IP in 3CX to that of AT&T's SIP interface, but now I've realized that it's not ideal because AT&T only allows SIP traffic down that line.

Can I simply change the public IP in 3CX to that of our data connection instead of the SIP connection? Will that mess up the SIP traffic at all? The network on the server is currently configured as outlined in this article for "multiple internet gateways", but the guide doesn't say anything about which interface's public IP should be used in 3CX. https://www.3cx.com/blog/docs/network-configurations-supported-3cx-phone-system/

 

[eddv123]

Interesting that you are doing this setup with AT&T trunking. I have not used their trunks however in my experience (I have setup this scenario multiple times) on premise servers are normally setup in this way for geographic and reasons dictated by local regulations (for example India and Singapore must have systems setup like this by law). https://www.3cx.com/community/threads/tata-communications-trunk-3cx-integration.70050/

In regards the actual question however 3CX can be set to use dynamic IP addressing (follow the guidelines here on how to do this post install) https://www.3cx.com/community/threads/change-wan-ip.60345/

However success of this would depend on how this is setup from the provider, for example do they provide a single public IP address down the SIP provided line only ? if so they will only be looking for traffic to > from this address (IP authenticated SIP trunk) and any change without prior consultation with them would result in a failure of calls.

 

[Dutchigander]

So from AT&T we have both voice and data services, but they come in on separate VLANS from their equipment. One VLAN allows SIP traffic only, the other allows data. We have public IPs for both lines, however the public IP that I put in 3CX is for the SIP line. Basically I just need to know if I can change that without screwing everything up. The AT&T trunk is routed manually out the 2nd NIC, so in theory changing the public IP should affect that, right?

 

[eddv123]

From what you have described I would say that the Public IP for the SIP line (voice) needs to stay as such (and data as data).

If you were provided a block of IP's for a single line/account this would be OK to use an alternate however I think if this case the line dictates the IP used.

Unless any specific users of AT&T can advise on here I would check with them in regards to your options and see if you can perhaps get a single line option.