Finding IP Address for IPhone

Unfortunately the responses are not completely correct. In a 3G/4G network every device gets an IP address, but THAT's NOT the IP address that you see when going to sites like www.whatismyip.com. That's the address that the Telco presents to the external world, not the device IP address.

Telcos such AT&t, Verizon, Telefonica and similar assign a "private" IP address that is only valid in their network. This is similar to the internal IP address that you have in your phone when connect to the house wireless, but if you check in www.whatismyip.com you get the external IP address of your wireless router (You can check that those are different addresses). What Telcos do is known as NAT or PAT. The reason is that the current version of IP has a very limited number of available IP addresses, and all those million of devices cannot get public IP addresses (like the one you see in whatismyip.com). Actually several devices share that external IP address.

Unlike Android devices where you can get the IP that the telco assigned to the device, iOS does not present that information to the user (unless you jailbreak the device or have an App).

Although the address that whatismyip presents is not your real IP, it is the one that the external world recognizes so it suffices for most purposes.

What you see on whatismyip.com is the IP address you get from your mobile provider, on which it depends what kind op IP you get. Very often 3G networks are NATted, meaning that you get an IP address from the range 10.0.0.0/8 which cannot be reached from outside.