Business Insider recently featured OpenSignalMaps on their website:
AntennaSearch.com vs OpenSignalMaps’ Tower Map
They claim our Tower Map is similar to antennasearch.com, but there are differences between the two. AntennaSearch compile their tower data from government databases. This gives them very accurate tower locations, but only for towers in the government database. The law requires that only towers above 200ft have to be registered, and in practice you find many towers just under this to escape the requirement. So if you compare AntennaSearch and OpenSignalMaps for any given location you’ll see many more towers on our site.