Re: sprint spark
It also brings in much faster LTE speeds. I got in the 20-30 Mb/s download speed range when I used it when I was visiting Chicago a few times this year.
It's on as long as LTE is on, although the spinning LTE spark logo is there regardless of whether you're actually on part of the Spark network. There are only a handful of cities that have been upgraded so far though.
Sent from my HTC One M8