3GPP 24.501 v20.0.0 — the document's own text

5.5.1.2.1 General

Taught in 6. Getting on the network, and getting a connection through it (CT1 — the group that writes what your phone says, in depth), 4. Inside TS 24.501, the document at the centre (CT1 — the group that writes what your phone says, overview).

This procedure can be used by a UE for initial registration for 5GS services.

When the UE initiates the registration procedure for initial registration, the UE shall indicate "initial registration" in the 5GS registration type IE. When the UE initiates the registration procedure for emergency services, the UE shall indicate "emergency registration" in the 5GS registration type IE. When the UE initiates the initial registration for onboarding services in SNPN, the UE shall indicate "SNPN onboarding registration" in the 5GS registration type IE. When the UE initiates the initial registration procedure for disaster roaming services, the UE shall indicate "disaster roaming initial registration" in the 5GS registration type IE.

If the MUSIM UE initiates the registration procedure for initial registration and indicates "emergency registration" in the 5GS registration type IE in the REGISTRATION REQUEST message, the network shall not indicate the support of:

the N1 NAS signalling connection release;
the paging indication for voice services;
the reject paging request; or
the paging restriction;

in the REGISTRATION ACCEPT message.