—Knowing the position of an Internet host enables location-aware applications and services, such as restriction of content based on user’s position or customized advertising. Active IP geolocation techniques estimate the position of an Internet host using measurements of the end-to-end delay between the target and a number of landmarks (hosts whose positions are known in advance). We present an IP geolocation method that operates in a crowdsourcing perspective and uses mobile devices as landmarks, since their position can be easily computed using the GPS unit. A specific calibration has been included to take into account the particular operating environment which, differently from the past, includes the presence of wireless links.