user1049: I have a Mega board and a GSM shield. I'm using Arduino's example "TestWebServer". The serial monitor shows that the GSM is connected, and returns a IP. 
However, the IP is always 10.X.X.X. Isn't that a internal network IP address? How should I get the SIM cards IP? Thanks!

user1113: The SIM card does not have an IP address. When the data connection is made to your GSM APN it is assigned an IP in a similar way to DHCP. Often the address is the same after the first connection as the service provider will link that to your SIM for audit purposes. If you setup a private APN then you can arrange to have specific range allocated to your SIM card(s). This is normally only done for security of volume reasons.

1049: <p>I have a <a href="http://arduino.cc/en/Main/ArduinoBoardMega2560" rel="nofollow">Mega board</a> and a <a href="http://arduino.cc/en/Main/ArduinoGSMShield" rel="nofollow">GSM shield</a>. I'm using Arduino's example "TestWebServer". The serial monitor shows that the GSM is connected, and returns a IP. </p>

<p>However, the IP is always 10.X.X.X. Isn't that a internal network IP address? How should I get the SIM cards IP? Thanks!</p>
 1113: <p>The SIM card does not have an IP address. When the data connection is made to your GSM APN it is assigned an IP in a similar way to DHCP. Often the address is the same after the first connection as the service provider will link that to your SIM for audit purposes. If you setup a private APN then you can arrange to have specific range allocated to your SIM card(s). This is normally only done for security of volume reasons.</p>
