SIM toolkit (STK)

The SIM Toolkit(STK) is a programming interface( API) between the Subscriber Identity Module (SIM) of a GSM cell phone and an application via which a mobile unit can be positioned.

The positioning information can be close to that of the Cell of Origin( COO). Additional capabilities such as the use of delay compensation, timing advance( TA), or network measurement report( NMR) can make the positioning information more accurate. In all cases, SIM Toolkit enables communication between the SIM card, which may contain additional algorithms for positioning, and a location server application, which may contain additional algorithms to support mobile positioning. STK Toolkit is a technique to obtain position information while the mobile device is in sleep mode.