This European Telecommunication Standard (ETS) specifies measurable performance requirements for signalling aspects of mobile stations. To allow implementation flexibility it has been chosen to specify requirements on the whole mobile station rather than to specify requirements on each OSI layer. As a consequence the performance requirements do not fit conveniently in specifications such as TS GSM 04.08 (layer 3 only) or TS GSM 04.06 (layer 2 only). The main aim of this ETS is to provide the justification for testing of requirements that are not included in other GSM specifications. Where specific requirements are included in other GSM specifications they are not duplicated here. Mobile Stations have to perform a wide variety of functions. As a consequence most performance measurements have to be made under a set of defined conditions: where necessary, these are included in this ETS. Where necessary certain assumptions are made about the interaction times between the mobile equipment and the SIM. If the (test) SIM does not respond within the assumed time then appropriate allowances shall be made. Additionally, it is intended that this ETS should contain sufficient requirements to enable some undefined network timers in TS GSM 04.08 to be calculated.