To locate a mobile telephone geographically, there are two general approaches: some form of radiolocation from the cellular network, or to use a Global Positioning System receiver built into the phone itself. Both approaches are described by the radio resource location services protocol (LCS protocol). Depending on the mobile phone hardware, one of two types of location information can be provided to the operator. The first is Wireless Phase One (WPH1), which is the tower location and the direction the call came from, and the second is Wireless Phase Two (WPH2), which provides an estimated GPS location.