AT&T notes in a filing with the SEC today that it intends to sunset its legacy 2G GSM network by January 1st, 2017, the first time it's given a hard date for the shutdown. The carrier has already begun the process of refarming existing 2G spectrum for the deployment of additional 3G / 4G bandwidth — in New York City, for example — but we now know that it expects the transition to be 100 percent complete about four and a half years from now. Geographically speaking, much of AT&T's footprint remains at 2G speeds, but at this point, it's unclear how much (if any) of it will be turned off rather than upgraded. (By population, the majority of the network is already covered by HSPA.)

It's been a long time since 2G was pervasive in AT&T's handset portfolio, and it says that as of last month, just 12 percent of its postpaid customers were using 2G devices — a number that can likely be reduced to near zero through upgrade incentives over the course of the next several years. A larger impact might exist in the machine-to-machine market, where AT&T has been aggressively certifying network-compatible modems; it's unclear at this point how many industrial devices that transmit data over AT&T's EDGE airwaves will ultimately be affected and will need to be upgraded or decommissioned.