Description
The Registered Public Land Mobile Network (RPLMN) is a core identifier within 3GPP mobility management protocols. It represents the specific Public Land Mobile Network (identified by a Mobile Country Code and Mobile Network Code - MCC-MNC) where a User Equipment (UE) has successfully performed a registration procedure and is currently considered 'attached' or 'registered'. This registration grants the UE authorization to access that network's services, including voice, data, and supplementary services. The RPLMN is stored in the UE's non-volatile memory and in the network's subscriber database (e.g., HSS/UDM). It is a key parameter used by the UE and the network to manage the UE's state and service continuity.
Architecturally, the RPLMN is central to the network selection and reselection processes defined in the Non-Access Stratum (NAS) protocols. When a UE is powered on or loses coverage, it searches for available PLMNs. The selection algorithm prioritizes the RPLMN if it is available, as this is the network the UE is already subscribed to for service. The concept is integral across 3GPP generations, from GSM/GPRS (where it might be referred to in the context of the Location Area) through UMTS and LTE, to 5G. In 5G, the RPLMN is maintained as part of the UE's 5G Mobility Management (5GMM) context and is crucial for initial registration and mobility registration updates.
How it works involves a multi-step interaction between the UE and the core network. Upon successful authentication and registration with a network, that network's PLMN ID becomes the UE's RPLMN. The network confirms this registration in its core network entities. The UE will then periodically or upon specific triggers (like movement) report its location to this RPLMN. If the UE moves out of the RPLMN's coverage area, it may register with a new PLMN (which then becomes the new RPLMN) if a roaming agreement exists, or it may attempt to re-select the RPLMN when it returns to coverage. The RPLMN is distinct from but related to the Equivalent PLMN (EPLMN) list, which contains networks considered equivalent to the RPLMN for cell reselection and handover purposes, facilitating seamless mobility.
Purpose & Motivation
The RPLMN concept was created to provide a clear, unambiguous reference point for a mobile device's 'home' or currently active network within a global ecosystem of multiple, independent operator networks. It solves the fundamental problem of network identity and service authorization in a roaming environment. Before such standardized concepts, managing subscriber mobility across different operator domains would be chaotic and insecure.
Historically, as cellular networks evolved from single-operator deployments to national and international roaming consortia, a mechanism was needed to track where a subscriber was registered and which network was responsible for providing and billing for services at any given time. The RPLMN provides this anchor. It addresses the limitation of simply detecting a radio signal by tying service access to a formal registration and subscription relationship. It enables features like roaming (by allowing a visited PLMN to know the subscriber's home PLMN for billing and service profile retrieval), prioritized network selection (always try to use your registered network first), and efficient mobility management (the network knows which set of cells and tracking areas are associated with a given RPLMN). Its persistence in the UE's memory allows for faster service recovery after power cycles or temporary loss of signal.
Classification
Detected Changes Across Releases
from 3GPP Change RequestsSpecific changes extracted from the „Change history“ tables of 3GPP specifications (194 CRs across 5 releases). Complements the general historical overview above with the evidence-based evolution of this function.
Studied in Rel-4, normative work from Rel-15.
In Release 15, enhancements to the RPLMN function included clarifications on the procedure for determining the registered PLMN and the correct deletion of the Extended Local Emergency Numbers List upon a PLMN change. The release also introduced the storage of the Configured NSSAI when the PLMN is changed and provided clarifications on the handling of back-off timers and the Equivalent PLMN (EPLMN) list during PLMN selection.
- Storing Configured NSSAI when the PLMN is changed TS 24.501CR0203
- Handling of error case when UE gets URSP from VPLMN TS 24.501CR0256
- Adding EPLMN list related descriptions TS 24.501CR0102
- Storing of MPS indicator in non-volatile memory of mobile TS 24.501CR0123
- Resolution of editor's note on equivalent PLMN list TS 24.501CR0141
- Resolution of editor's note on sub-states of state 5GMM-REGISTERED TS 24.501CR0145
+ 24 more changes
In Release 16, the RPLMN function was extended to include support for Stand-alone Non-Public Networks (SNPNs) and to clarify procedures for unified access control within SNPNs. The release introduced more detailed handling for scenarios where a UE is not allowed to access SNPN services via a PLMN and specified the broadcasting of SNPN identities in shared networks. Additionally, it provided clarifications on the use of the Allowed NSSAI within an equivalent PLMN and on the handling of the "S-NSSAI not available" condition.
- Adding support for SNPNs (Stand-alone Non-Public Networks) TS 24.501CR0963
- Serving PLMN rate control, general description TS 24.501CR0972
- Serving PLMN rate control, activation TS 24.501CR0973
- Introduction of non-public network TS 24.501CR1054
- PLMN ID and NID provided to the lower layers TS 24.501CR1055
- Adding support for unified access control in SNPNs (Stand-alone Non-Public Networks) TS 24.501CR1134
+ 47 more changes
In Release 17, enhancements to the RPLMN function included new procedures for de-registration of UEs registered for SNPN onboarding services and for UAS (UAV) registered as normal UEs. The release also introduced specific handling for PLMNs in a disaster condition, including a definition for being registered for disaster roaming services. Furthermore, it provided solutions for managing CAG IDs of a PLMN beyond certain encoding limits and clarified UE behavior when receiving a rejected NSSAI with a specific cause.
- De-registration for SNPN onboarding registered UE TS 24.501CR3321
- UAV registered as normal UE TS 24.501CR3563
- De-registration for onboarding registered UE TS 24.501CR3632
- PLMN with disaster condition TS 24.501CR3585
- Adding definition for registered for disaster roaming services TS 24.501CR3825
- Alignment to KI#2 conclusions on EPLMN list TS 24.501CR3606
+ 53 more changes
In Release 18, enhancements to the RPLMN function included the ability for the UE to store the NID value of a registered SNPN in non-volatile memory and the introduction of procedures to handle when a Forbidden PLMN (FPLMN) is declared an allowable PLMN by the network. Furthermore, clarifications were made regarding the applicability of the equivalent PLMN list when the UE registers to two PLMNs and for the storage of rejected NSSAI associated with an Equivalent PLMN (EPLMN).
- Providing registered SNPNs TS 24.501CR4835
- Equivalent SNPN usage for mobile identity selection TS 24.501CR4840
- Providing VPLMN specific URSP TS 24.501CR5169
- Introduction of MDT enhancements to support Non-Public Networks TS 37.320CR0128
- Introduction of mobile IAB TS 38.331CR4457
- 5GMM cause code #15 indicating Satellite NG-RAN not allowed in PLMN TS 24.501CR6249
+ 27 more changes
In Release 19, the RPLMN function was enhanced with specific clarifications and handling rules for scenarios involving high-priority access, disaster roaming services, and authentication rejections. Key updates included refined procedures for the PLMN-specific attempt counter reset and the handling of the Equivalent PLMN (EPLMN) list upon receiving certain reject causes. Furthermore, the release introduced detailed conditions for the removal of memorized PLMN identities and clarified timer T3540 behavior for UEs with high-priority access in a selected PLMN.
- Storage and replacement of RAT utilization control information associated to the current PLMN TS 24.501CR6460
- Timer T3540 handling for causes triggering cell or PLMN selection TS 24.501CR6238
- Addition of a condition for the removal of memorized PLMN and SNPN Ids. TS 24.501CR6548
- Missing NOTE for T3540 for a UE with high priority access in selected PLMN or SNPN TS 24.501CR6546
- PLMN-specific counter reset TS 24.501CR6602
- Handling of EPLMN list and attempt counters due to AUTH reject TS 24.501CR6642
+ 13 more changes
Explore further
Broader topics and technologies where RPLMN plays a role.
Defining Specifications
3GPP specifications that define or reference RPLMN, with the latest known release. Sourced from the 3GPP document catalog — see methodology.
| Specification | Title | Release |
|---|---|---|
| TR 21.905 vj00 | 3GPP Technical Terms and Definitions | Rel-19 |
| TS 24.501 vj50 | 5G NAS Protocols Specification | Rel-19 |
| TS 36.331 vj00 | LTE RRC Protocol Specification | Rel-19 |
| TS 37.320 vj00 | Minimization of Drive Tests (MDT) Overview | Rel-19 |
| TS 38.331 vj00 | NR Radio Resource Control (RRC) Protocol Specification | Rel-19 |