AT&T has certified a 3G chip module that the manufacturer calls the world’s smallest, but that doesn’t mean the carrier is going after toddlers as its last untapped customer base. The U-blox SARA-U260 module, which measures 16 by 26 millimeters, can handle voice calls. But it’s not designed for really small phones for tiny hands. Instead, it’s meant to carry the small amounts of data that machines are sending to each other over the “Internet of things,” where geographic coverage — 3G’s strong suit — matters more than top speed. That means things like electric meters, fitness watches and in-car devices that insurance companies use to monitor policyholders’ driving. The AT&T certification means device makers can now start building products around the U260 module for use on the carrier’s network. The U260 module is equipped for use on 3G networks with roaming to 2G where necessary, such as in rural areas.