How to check if the ISP uses Carrier-grade NAT (CGN)

It has been more and more common that mobile telephone operators has changed to CGN for their internet connections to save IPv4 addresses. CGN is no problem for most subscribers if they only need to browse the web sending emails etc. But it makes communication in the other direction, from outside Internet and in, impossible. This means that a Remoterig Radio-RRC cannot be used with an ISP using CGN. For the control-RRC it’s OK. In most cases it’s possible to get a subscription with real public IP-addresses from the ISP but in some cases you have to pay extra for it.

More info about CGN

To check if your ISP is using CGN you need to connect a PC to the router which has the a SIM card installed for the ISP you want to test.

When you are up and in connection with the Internet and can browse the web go to

or any similar page which will show from which public IP address your request is coming. This address is always a public IP-address, nothing else works.

After that, login to your router and look at the status page. The router will report which WAN IP-address it has got from the ISP.

If it shows the same IP-address as whatsmyip everything is OK and it will work with Remoterig.

If the router shows another WAN IP-address it’s NOT OK, the ISP is using CGN.

If CGN is in use the router often shows a WAN IP address like or

If your ISP is using CGN you must talk to him and tell him that you cannot use a subription with CGN you must have a public IP-address.

Note! This is only important at the Radio side.

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