T-Mobile Sonic 4G Mobile HotSpot review Summary: T-Mobile has one of the fastest mobile data networks in the U.S. and this new portable hotspot device supports their fastest 42.2 Mbps network. By Matthew Miller | November 11, 2011 -- 08:24 GMT (00:24 PST) Follow @palmsolo Previous | Next Image 4 of 11 Under the battery cover you will find the battery, SIM card slot, and microSD card slot. Topic: Mobility Kick off your day with ZDNet's daily email newsletter. It's the freshest tech news and opinion, served hot. Get it.