Some carriers use "small cells" to boost their coverage, because these relatively tiny transmitters are 1.) a lot cheaper, and 2.) more inconspicuous than their traditional counterparts. Verizon is one of those carriers -- in fact, it's planning to install 400 small cells in certain high-traffic areas in San Francisco starting this second quarter. These devices (designed by Ericsson) will be integrated into street lamps and will generally blend into the surroundings within SF's Financial District, SOMA, Market Street and North Beach neighborhoods. The cells do have a limitation, though: each one can only cover an area that has a 250 to 500-foot radius. That's why for this particular rollout, Verizon plans to lay down the structure for a dense network made up of numerous small cells covering some parts of the city only.