Shipments of mobile phones with built-in GPS capability are expected to more than quadruple by 2011, according to a report released by research firm iSupply on Thursday.

GPS-enabled mobile phone shipments will increase from 109.6 million units in 2006 to 444 million units by 2011. By 2011, 29.6% of all mobile phones shipped will have GPS. As a comparison, only 11.1% of phones shipped in 2006 had GPS, the report found.

The increase is attributed to a mandate created by the United States government for Enhanced 911 capability on cellular and voice-over-IP telephone calls.

In 1996, the Federal Communications Commission mandated a two-phase implementation of E911 for cellular carriers that had to be completed by the end of 2005. As part of Phase I, carriers were required to provide the phone number and location of the cell tower that delivered a 911 call to the Public Safety Answering Point. In Phase II, carriers were required to have the ability to triangulate a call to within 100 meters. The FCC also added assisted GPS, or A-GPS, as an alternate technology for locating calls.

Qualcomm, the dominant supplier of CDMA technology, in 2000 started integrating GPS processors into its digital baseband chips. Due to this development, the United States and South Korea -- which largely use CDMA -- will be the leading countries with GPS-enabled mobile phones. Europe will be the next largest GPS-enabled phone market, according to iSuppli.

Additional developments in location-based services will encourage more suppliers to develop power-efficient and affordable A-GPS technologies. Such services can assist in locating users, providing turn-by-turn navigation, conducting location-based search, and tracking, among other benefits.

Another report released by J.D. Power and Associates this week shows that phones equipped with GPS are in high demand by mobile users. More than 40% of users want their smartphones to have GPS capabilities.

Looks like mobile users will get what they want in the next three years.