My 3GPP TS 23.003 notes

International Mobile Subscriber Identity (IMSI) § 2.2

IMSI is composed as shown:

IMSI is composed of three parts:

1. Mobile Country Code (MCC) consisting of three digits. The MCC identifies uniquely the country of domicile of the mobile subscription;
2. Mobile Network Code (MNC) consisting of two or three digits for 3GPP network applications. The MNC identifies the home PLMN of the mobile subscription within its country of domicile, or it identifies together with MCC and NID the mobile subscription's SNPN. The length of the MNC (two or three digits) depends on the value of the MCC. A mixture of two and three digit MNC codes within a single MCC area is not recommended and is outside the scope of 3GPP TS 23.003.
3. Mobile Subscriber Identification Number (MSIN) identifying the mobile subscription within a PLMN or SNPN.

5G Globally Unique Temporary UE Identity (5G-GUTI) § 2.10

Introduction § 2.10.1

The purpose of the 5G-GUTI is to provide an unambiguous identification of the UE that does not reveal the UE or the user's permanent identity in the 5G System (5GS). It also allows the identification of the Access and Mobility Management Function (AMF) and network. It can be used by the network and the UE to establish the UE's identity during signalling between them in the 5GS. See 3GPP TS 23.501 [119].

The 5G-GUTI has two main components:

• one that identifies the AMF(s) which allocated the 5G-GUTI; and
• one that uniquely identifies the UE within the AMF(s) that allocated the 5G-GUTI.

Within the AMF(s), the mobile shall be identified by the 5G-TMSI.

The Globally Unique AMF Identifier (GUAMI) shall be constructed from the MCC, MNC and AMF Identifier (AMFI).

The format and size of the 5G-GUTI is therefore the following:

<5G-GUTI> = <GUAMI><5G-TMSI>, where <GUAMI> = <MCC><MNC><AMF Identifier> and <AMF Identifier> = <AMF Region ID><AMF Set ID><AMF Pointer>

Structure of the 5G-S-Temporary Mobile Subscriber Identity (5G-S-TMSI) § 2.11

The 5G-S-TMSI is the shortened form of the 5G-GUTI to enable more efficient radio signalling procedures (e.g. paging and Service Request). For paging purposes, the mobile is paged with the 5G-S-TMSI. The 5G-S-TMSI shall be constructed from the AMF Set ID, the AMF Pointer and the 5G-TMSI:

<5G-S-TMSI> = <AMF Set ID><AMF Pointer><5G-TMSI>

Definition of Access Point Name § 9

In the GPRS backbone, an Access Point Name (APN) is a reference to a GGSN. To support inter-PLMN roaming, the internal GPRS DNS functionality is used to translate the APN into the IP address of the GGSN.

Definition of Data Network Name § 9A

In 5GS, the Data Network Name (DNN) is equivalent to an APN in EPS. The DNN is a reference to a data network, it may be used e.g. to select SMF or UPF.

The requirements for APN in clause 9 shall apply for DNN in a 5GS as well.

NR Cell Identity (NCI) and NR Cell Global Identity (NCGI) § 19.6A

The NR Cell Global Identity (NCGI) shall be composed of the concatenation of the PLMN Identifier (PLMN-Id) and the NR Cell Identity (NCI) as shown in figure 19.6A-1 and shall be globally unique:

MCC + MNC + NCI

The NCI shall be of fixed length of 36 bits and shall be coded using full hexadecimal representation. The exact coding of the NCI is the responsibility of each PLMN operator. For more details on NCI and NCGI, see 3GPP TS 38.413.

NOTE: In the 5G Core Network protocols, when the NCGI needs to be identified in the context of Standalone Non-Public Networks (SNPN), the Network Identifier (NID) of the SNPN is included as part of the NCGI Information Element (see 3GPP TS 29.571); this is a protocol aspect that does not imply any change on the system-wide definition of the NCGI.

Numbering, addressing and identification for 5G System (5GS) § 28

Introduction § 28.1

This clause describes the format of the parameters, identifiers and information used for the 5G system. For further information on these, see 3GPP TS 23.501, 3GPP TS 23.502 and 3GPP TS 23.503.

NAI format for SUPI see § 28.7.2

NAI format for SUCI see § 28.7.3

NAI format for 5G-GUTI see § 28.7.8

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