We had an office at 385 Sherman Avenue in Palo Alto, CA for several months, where we had signal strength with our Franklin U300 3G/4G card of 70% - 80% on the 3G network. We just moved about 1.5 miles away to 3260 Hillview Avenue, which is well within Sprint's 3G coverage area on the Sprint coverage map. Our coverage ranges between 0% and 6%. AT&T and T-Mobile have five bars.
Our same card works just fine anywhere else, so it's not our hardware.