USIM Application Toolkit (USAT) is the equivalent of
STK for
3G networks. USAT enables the
USIM to initiate actions which can be used for various
value added services delivered over mobile devices.USAT takes advantage of the multiapplication environment of 3G devices by not activating until a specific application has been selected, unlike STK which is activated at startup. Some functions are card related rather than application related.USAT is defined in standard
3GPP 31.111 for 3G.
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