I live in an area where I can't get cable or DSL internet. So I use the sprint aircard with unlimited data. I trade index futures every day and live off my trading, so yes it is viable. The only problem I have is it will disconnect every so often, but I can reconnect within 10 seconds. Also, there is a slight lag. If you trade for larger moves, say 2-5 ES points at a time, there's no problem. I wouldn't suggest trying to scalp ticks off it.