The present document discusses and describes the CT1 aspects of the 5G System phase 1. In particular, these CT1
aspects include the non-access-stratum (NAS) functions to be performed by the user equipment (UE) in idle mode and
the NAS signalling procedures between the UE and the 5G System (5GS) phase 1.
The present document also considers the requirements on the NAS between the UE and the core network which arise
from specific services such as public warning system (PWS), SMS over NAS, emergency services, location services
(LCS), multimedia priority services (MPS), and also network functions such as access control, security, QoS, IMS,
network sharing, charging, congestion and overload control. In addition, the document considers the case of network
slicing as well as interworking with E-UTRAN connected to EPC.
The present document is intended as a holding place for CT1 5GS material until it stabilises sufficiently to be moved to
appropriate 3GPP technical specifications.