3CX Behind Mobile (4G) provided broadband (with CGNAT)

Discussion in '3CX Phone System - General' started by marcusjclifford, Oct 18, 2016.

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  1. marcusjclifford

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    Hi, my 3CX environment works perfectly behind my FTTC provided broadband, for that though I have a standard routable IPv4 IP address assigned to the external interface. Because I use NAT on the internal side of the network I have setup port forwarding etc and it works perfectly.

    My question is that, for backup, we have now bought a 4G Router / Modem. With this I can set it up to either be a router, or work as a simple modem and pass the IP address allocated to the LAN. If I use it in “modem mode” then I can pass the IP address to the WAN port of my existing router, hence saving any reconfiguration needs.

    However, the IP address I am given by my mobile provider is a private 10.x.x.x IP address, I believe this is called CGNAT (Carrier Grade NAT). I therefore cannot do port forwarding or such at that level as it is a shared environment.
    Skype and such works fine, as does most other Internet activities, but I cannot get my 3CX infrastructure to work, I presume because of the networking setup.

    Does anyone have experience of advice of operating behind CGNAT. Perhaps the use of a STUN server or Keep-Alives?

    Thanks in advance.
    Marcus
     
  2. leejor

    leejor Well-Known Member

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    I think that you are going to have several hurdles. The fact that you won't be able to do port forwarding is a big one, and may be a deal killer. I would talk to the mobile provider and explain what you hope to do and see if they feel it is feasible, or better yet, run a test set-up PBX. The other thing to consider, and it's also a big one...3CX versions 14 and 15 pretty much insist on you having a static public IP. So..if that IP is going to change, at some point, you are going to have to work out how that will be accomplished ... DDNS, STUN? Both are not really supported or recommended any longer. I'm not saying that it is impossible, just that you may have to do some trial and error to accomplish a quick and relatively seamless cut-over.

    Hopefully others may have some suggestions.
     
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