The Scope of this GTS is to clarify how interworking can be obtained between phase 2 mobile stations and phase 1 infrastructure. The objective is to obtain this without changing the consolidated set of phase 1 specifications. This Technical Report specifies the necessary amendments to the phase 1 infrastructure so that an acceptable service is offered to mobile stations of phase 2, guaranteeing that a phase 2 mobile station obtains all phase 1 services. This report outlines the necessary changes as well as the necessary controls and clarifications with regard to phase 1 implementation, which should be performed to the different interfaces in phase 1 infrastructure before phase 2 mobiles are offered service.