As telecom companies rev up the newest generation of mobile service, called 5G, they're shutting down old networks — a costly, years-in-the-works process that's now prompting calls for a delay because many products out there still rely on the old standard, 3G.
AT&T is scheduled to be the first carrier to shut down its 3G network on Feb. 22. T-Mobile will shut down its 3G network by summer and Verizon in December.
