There are different types of EPS security context, namely 'native and mapped'.
These types point to the origin of the context: a native EPS security context is a context whose Kasme was created during a run of EPS AKA, while a mapped EPS security context is converted from a UMTS security context when the UE moves to LTE from UTRAN or GERAN.
A mapped EPS security context is always 'full' while a native EPS security context may be full or partial.
A partial native EPS security context is created by an EPS AKA tun, for which no corresponding successful NAS SMC procedure has been run; in other words, a partial native EPS security context is always in state 'non-current'.
After having been put into use by running a NAS SMC procedure, a partial native EPS security context becomes full as the NAS security algorithms and the NAS keys have been agreed between the UE and the MME.
