This is a simple app to get your local IP (the one your phone has been given by your ISP) and your Internet IP (the one visible through Internet).
Most of the time they differ because your ISP doesn’t have enough public IP (Internet routable IP) so they give you unroutable IP and use NAT (Network Address Translation) to hide your phone behind a routable Internet IP address.
This app also gives you the host name associated with your internet IP (reverse lookup).
Download : MyIP-1.4
The app is using http://ip.dedikewl.fr/ to get Internet IP.