[ericwp]

Make sure you have proper coverage for the aircard in your area.
Verizon should be EVDO coverage, ATT should have 3g coverage and not sure about T-Mobile, we don't use T-Mobile cards at work.

It is called mobile broadband and the speeds should equal DSL or be greater.
Not all carriers have the "high speed" coverage for the aircards in all areas. Some default to lower speeds such as 1X for Verizon and Either Edge or GPRS for ATT. Double check with whomever you are going to go with. Go to the websites for the respective carriers and do a search for coverage and types of coverage by zip codes. Ask your neighbors or people from your area also, best way to do research to see what is best for you.

From my experiance installing, buying, fixing, deploying these cards, verizon has the best coverage across the the good ole USA.

Also there might be a limit as to how much data you can use per month, depending on the plan you purchase..the average is 5GBs a month.