The S1 Application Protocol (S1AP) provides the control plane signalling between E-UTRAN and evolved packet core (EPC). The used interface is S1-MME which is located between eNB and MME. The services provided by the S1AP are divided to UE associated and non UE associated. The UE associated services are related to one UE and the non UE associated services are related to the whole S1-MME interface. The S1AP is transfered over SCTP. The S1AP protocol is defined in TS 36.413. The S1AP protocol provides transport function between UE and MME by offering NAS signalling transport. The NAS protocol provides mobility management and session management between the User equipment (UE) and Mobile Management Entity (MME). The NAS protocol is defined in TS 24.301. The S1AP/NAS Client Suite has been designed to act as a malicious MME that sends exceptional requests to the tested entity. The supported test target is eNodeB or UE.