Non-Static GSM IP address DNS solution?

Hi,

I am using the CPX4 with GSM. My primary internet connection will be via GSM (ie dynamic IP address). I need to wait for an XML http message from some application (needing to send info to a URL), then reply to it. The problem I need help with is:

  1. How do I keep ‘listening’ out for the message (example code)?

  2. The application sending the XML message needs the CPX4 IP address to be identifiable via a URL. My thinking is to register with dyn.com (or similar) and have the CPX4’s IP address resolved via dyn.com; then have the application pointing to dyn.com to always have the latest CPX4 IP address. Is there any advice in relation to this approach or any other examples/threads I can look at?

  3. The idigi server obviously has figured this out. I am also aware that the mobile operators may have some block on this traffic via NAT, etc.
    Is it possible to have non RCI XML messages sent (by this ) to the server, the ‘reroute them to CPX4’ and then have the CPX4 send a reply via the idigi platform?