That's pretty lame. What IP you wanted to drive where there is no cell connectivity rt all, say Mongolia?
Another commenter speculated that when you're out of service, the software correctly identifies that there is no tower to connect to and stops trying. But when you're in service, the code repeatedly tries to do the 3G handshake because it can see a valid tower.
One can only hope that "smart" will have very bad associations in the future (for the general public).