freedns.affraid.org DNS Android Updater is a Dynamic DNS client that connects to Free DNS servers to update your device IP. It only works with the "Randomized Update Token" option: simply set the URL token in proper Free DNS Android Updater menu option and press play button.

Information about execution in a phone using 3G network: usually, those devices run behind a proxy of the respective ISP that block inbout connections so keep in mind it is carrier dependant (to test if it works, ping the address informed by this app; if you get the replies, then it is accessible).