Description
The term 'PS' in 3GPP standards has two distinct and important meanings, differentiated by context.
As **Packet Switched (PS)**, it refers to the architectural domain and service type where user data is formatted into packets for transmission, as opposed to the Circuit Switched (CS) domain used for traditional voice calls. The PS domain is the foundation of mobile broadband. In 5G, the entire core network is packet-based (5GC), but the term remains relevant historically and in interworking. A PS connection involves establishing a Packet Data Protocol (PDP) context in GPRS/UMTS or a PDN Connection/EPS Bearer in LTE, which defines the data path between the UE and an external packet data network (e.g., the internet). Key network functions in the PS domain include the Serving GPRS Support Node (SGSN) and Gateway GPRS Support Node (GGSN) in 2G/3G, the Serving Gateway (S-GW) and Packet Data Network Gateway (P-GW) in LTE/EPC, and the User Plane Function (UPF) in 5GC. These nodes handle packet routing, mobility anchoring, policy enforcement, and charging.
As **Public Safety (PS)**, particularly in specifications related to sidelink (e.g., 23.xxx series for ProSe, 24.xxx for protocols), it denotes applications and network features designed for mission-critical use by first responders (police, fire, ambulance) and other government agencies. Public Safety communications require high reliability, availability, security, and direct mode operation when network infrastructure is damaged or unavailable. 3GPP has standardized features like Proximity Services (ProSe) and Mission Critical Services (MCS) to meet these needs. A key enabler is device-to-device communication over the PC5 sidelink interface, allowing direct UE-to-UE communication (PS-LTE, PS-NR) without traversing the network infrastructure. This includes functions like direct discovery, direct communication, and UE-to-Network Relay.
The two meanings converge in modern networks: Public Safety services increasingly rely on the packet-switched infrastructure for broadband data applications (video, data sharing) and use the PS (Packet Switched) domain for network-connected operations, while also leveraging direct PS (Public Safety) sidelink for resilience.
Purpose & Motivation
The **Packet Switched** meaning originates from the fundamental evolution of mobile networks from voice-centric circuit-switched systems to data-centric packet-switched systems. Early GSM networks were optimized for circuit-switched voice. The introduction of GPRS (General Packet Radio Service) in 2G created the PS domain to enable efficient, 'always-on' internet access by sharing network resources statistically. This solved the problem of inefficient dedicated circuits for bursty data traffic, enabling the mobile data revolution. Each generation (3G UMTS, 4G LTE, 5G NR) has enhanced the PS domain with higher speeds, lower latency, and more sophisticated quality of service (QoS) management.
The **Public Safety** meaning arose from the need for commercial mobile network technology to support the stringent requirements of first responder communications. Traditionally, public safety relied on dedicated land mobile radio (LMR) systems like TETRA or P25. 3GPP standardization, starting in Release 12 and significantly expanding through Releases 13-15, aimed to leverage the economies of scale and advanced capabilities of LTE (and later 5G) to provide broadband public safety services. This addressed limitations of narrowband LMR systems, such as low data rates and lack of advanced multimedia services. The PS (Public Safety) work in 3GPP solves the problem of providing mission-critical push-to-talk (MCPTT), video, and data with high reliability, group communication management, and—critically—the ability to operate directly between devices when network coverage is lost, which is a life-saving requirement in disaster scenarios.
Classification
Detected Changes Across Releases
from 3GPP Change RequestsSpecific changes extracted from the „Change history“ tables of 3GPP specifications (43 CRs across 6 releases). Complements the general historical overview above with the evidence-based evolution of this function.
In Release 15, the primary new PS function introduced was the "PS Data Off" capability for 5GS, extending this control mechanism to next-generation networks. This release specified its interactions with services like MMTel voice/video, SMS over IP, and USSI, and provided corrections for its requirements when applied to non-3GPP accesses. Additionally, updates were made for WLAN-based ProSe direct discovery charging and roaming scenarios.
- MMTel -PS Data Off for 5GS TS 24.173CR0125
- 3GPP PS Data Off2 and MMTEL voice and MMTEL video TS 24.173CR0127
- PS Data Off for 5GS TS 24.341CR0089
- 3GPP PS Data Off2 and SMS over IP TS 24.341CR0090
- PS Data Off for 5GS TS 24.390CR0055
- 3GPP PS Data Off2 and USSI TS 24.390CR0056
+ 7 more changes
In Release 16, key enhancements for the PS function included the introduction of volume-based charging for VoLTE in the PS domain and refined support for PS Data Off. Specifically, improvements were made for PS Data Off operation via 5GS and the configuration of PS Data Off lists on the USIM for both home and roaming scenarios.
- Introduce description of volume based charging for VoLTE in PS TS 32.251CR0514
- Correction on PS data off TS 24.173CR0141
- Correct using XCAP and PS Data Off via 5GS TS 24.623CR0076
- PS Data Off list configuration in USIM for home and roaming TS 31.102CR0862
- Definition of the coding of the Home Network Public Key in EFSUCI_CALC_INFO TS 31.102CR0860
- Definition of the coding of the Home Network Public Key in EFSUCI_CALC_INFO TS 31.102CR0871
In Release 17, key enhancements for the PS function included the introduction of a "PS data off" capability for UEs operating in a Standalone Non-Public Network (SNPN) and the formalization of 5G Proximity Services (5G ProSe). This involved defining new ProSe configuration services and charging information for the Charging Function (CHF), as well as updating Elementary Files (EFs) for subscriber identity modules.
- 3GPP PS data off and UE in SNPN TS 24.173CR0148
- 3GPP PS data off and UE in SNPN TS 24.341CR0097
- 3GPP PS data off and UE in SNPN TS 24.390CR0058
- 3GPP PS data off and UE in SNPN TS 24.623CR0081
- 5G ProSe configuration related services and files TS 31.102CR0929
- Introduce 5G ProSe charging information to CHF CDR TS 32.298CR0901
+ 6 more changes
In Release 18, the PS function introduced enhancements for 5G ProSe direct communication, including support for U2U relay and new usage information reporting from the UICC. It also brought updates for Packet-Filter definitions and enabled support for Data Off exempt services in Dual Connectivity scenarios. Furthermore, enhancements were made to Minimization of Drive Tests to support operations within Non-Public Networks.
- Updates on 3GPP-Packet-Filter TS 29.061CR0553
- DF for 5G ProSe U2U relay TS 31.102CR0989
- Support DC in 3GPP PS Data Off exempt services TS 31.102CR1054
- Introduction of MDT enhancements to support Non-Public Networks TS 37.320CR0128
- Adding service for UICC 5G ProSe direct communication usage information reporting TS 31.102CR1048
- 5G ProSe usage information reporting TS 31.111CR0836
+ 1 more changes
In Release 19, key PS function enhancements focused on advancing ProSe (Proximity Services) capabilities, specifically introducing layer 3 multi-hop UE-to-Network relay communication. This required the definition of new Charging Data Record (CDR) parameters specific to this multi-hop relay operation. The release also included corrections and updates to existing CDR definitions for satellite ProSe, SMS, and general PS domain references to align with these new features.
- Add layer 3 multi-hop ProSe UE-to-Network relay communication related CDR parameters TS 32.298CR1033
- CDR parameters for charging of layer 3 multi-hop ProSe UE-to-Network relay communication TS 32.298CR1045
- Rel-19 CR 32.298 Correction of satellite ProSe and SMS information TS 32.298CR1051
- Rel-19 CR 32.298 Correction of reference for PS domain CDRs TS 32.298CR1066
In Release 20, the specific update for the PS function was an editorial update for publication following TSG SA approval, as indicated by the sole Change Request title. This administrative update did not introduce new technical procedures, interfaces, or capabilities for the Packet Switched domain compared to the previous release.
- MCC Editorial update for publication after TSG SA approval (SA#109) TS 23.700
Explore further
Broader topics and technologies where PS plays a role.
Defining Specifications
3GPP specifications that define or reference PS, with the latest known release. Sourced from the 3GPP document catalog — see methodology.
| Specification | Title | Release |
|---|---|---|
| TS 21.810 v1300 | Multi-mode UE Issues - Categories, principles and procedures | Rel-4 |
| TR 21.905 vj00 | 3GPP Technical Terms and Definitions | Rel-19 |
| TR 21.910 v1300 | Multi-mode UE Operation Principles | Rel-4 |
| TS 22.100 v1320 | UMTS Service Requirements Phase 1 | Rel-4 |
| TS 22.127 v1900 | Open Service Access (OSA) Requirements | Rel-9 |
| TS 22.135 vj00 | Multicall Supplementary Service Specification | Rel-19 |
| TS 22.233 vj00 | Packet-switched Streaming Service (PSS) Stage 1 | Rel-19 |
| TS 22.234 vd10 | 3GPP-WLAN Interworking Index Specification | Rel-13 |
| TS 22.803 vc20 | Proximity Services (ProSe) Study | Rel-12 |
| TS 22.811 v1700 | Network Selection Mechanisms Overview | Rel-7 |
| TR 22.813 va00 | Enhanced Voice Services for EPS Study | Rel-10 |
| TR 22.944 vj00 | UE Functionality Split Scenarios and Requirements | Rel-19 |
| TS 23.107 vj00 | UMTS QoS Framework | Rel-19 |
| TS 23.141 vj00 | Presence Service Stage 2 Architecture | Rel-19 |
| TS 23.207 vj00 | End-to-End QoS Framework for GPRS | Rel-19 |
| TS 23.221 vj00 | 3GPP System Architectural Requirements | Rel-19 |
| TS 23.236 vj00 | Intra Domain Connection of RAN Nodes to Multiple CN Nodes | Rel-19 |
| TS 23.700 vk00 | XR Services Application Enablement Layer | Rel-20 |
| TS 23.806 v1700 | Voice Call Continuity between CS and IMS | Rel-7 |
| TS 23.851 v1600 | Network Sharing Architecture for 3G Systems | Rel-6 |
| TR 23.976 vj00 | Push Service Requirements Analysis | Rel-19 |
| TR 23.979 vj00 | PoC over 3GPP Systems Architectural Requirements | Rel-19 |
| TS 24.141 vj00 | Presence Service Protocol Details | Rel-19 |
| TS 24.173 vj00 | Multimedia Telephony Service and Supplementary Services in IMS | Rel-19 |
| TS 24.305 vj00 | Selective Disabling of 3GPP UE Capabilities | Rel-19 |
| TS 24.341 vj00 | SMS over IP protocol details | Rel-19 |
| TS 24.390 vj00 | USSD over IMS Procedures | Rel-19 |
| TS 24.424 vj00 | XCAP over Ut for Supplementary Services MO | Rel-19 |
| TS 24.623 vj00 | XCAP Protocol for Supplementary Services | Rel-19 |
| TS 24.841 v1600 | Presence Service IP Multimedia Subsystem | Rel-6 |
| TS 25.410 vj00 | Iu Interface Introduction for UTRAN | Rel-19 |
| TS 25.412 vj00 | Iu Interface Signalling Transport Specification | Rel-19 |
| TS 25.413 vj00 | Radio Access Network Application Part (RANAP) | Rel-19 |
| TS 25.423 vj00 | UTRAN RNSAP Specification | Rel-19 |
| TS 25.444 vj00 | HNB User Data Transport Protocols | Rel-19 |
| TS 25.820 v820 | 3G Home NodeB Study Report | Rel-8 |
| TS 25.824 v800 | HSPA Evolution for 1.28Mcps TDD Study | Rel-8 |
| TS 25.913 v900 | Evolved UTRA and UTRAN Requirements | Rel-9 |
| TR 25.931 vj00 | UTRAN Signalling Procedures Examples | Rel-19 |
| TS 26.441 vj00 | EVS Audio Processing Introduction | Rel-19 |
| TS 26.442 vj00 | EVS Codec Fixed Point ANSI-C Code | Rel-19 |
| TS 26.443 vj00 | EVS Codec Floating-Point C Code | Rel-19 |
| TS 26.444 vj00 | EVS Codec Conformance Test Sequences | Rel-19 |
| TS 26.447 vj00 | EVS Frame Loss Concealment Procedure | Rel-19 |
| TS 26.450 vj00 | EVS Codec DTX System Level Aspects | Rel-19 |
| TS 26.451 vj00 | EVS Codec Voice Activity Detector (VAD) Specification | Rel-19 |
| TS 26.452 vj00 | EVS Codec Fixed-Point C Code Implementation | Rel-19 |
| TR 26.935 vj00 | Speech Codec Performance for Packet Switched Multimedia | Rel-19 |
| TR 26.937 vj00 | 3GPP PSS Characterization | Rel-19 |
| TR 26.952 vj00 | EVS Codec Selection, Verification & Characterization | Rel-19 |
| TS 27.060 vj00 | TE-MT Interworking for Packet Domain | Rel-19 |
| TS 28.652 vj00 | UTRAN Network Resource Model (NRM) IRP Information Service | Rel-19 |
| TR 28.816 vh00 | Charging for 5G Cellular IoT | Rel-17 |
| TS 29.061 vj00 | Packet Domain Interworking for PLMN | Rel-19 |
| TS 29.161 vc00 | 3GPP-WLAN Interworking Requirements | Rel-12 |
| TR 29.949 vj00 | VoLTE IMS Roaming Architecture & Procedures | Rel-19 |
| TS 31.102 vj40 | USIM Application Specification | Rel-19 |
| TS 31.111 vj30 | USIM Application Toolkit (USAT) Specification | Rel-19 |
| TS 31.113 v1800 | USAT Interpreter Byte Code Specification | Rel-8 |
| TS 31.121 vi50 | UICC-terminal interface test specification | Rel-18 |
| TS 32.102 vj00 | Telecom Management Physical Architecture Framework | Rel-19 |
| TS 32.140 vj00 | Subscription Management (SuM) requirements | Rel-19 |
| TS 32.141 vj00 | Subscription Management (SuM) Architecture | Rel-19 |
| TS 32.250 vj00 | Circuit Switched Offline Charging | Rel-19 |
| TS 32.251 vj00 | PS Domain Charging Management | Rel-19 |
| TS 32.252 vc00 | 3GPP WLAN Interworking Charging | Rel-12 |
| TS 32.271 vj20 | 3GPP LCS Charging Management Spec | Rel-19 |
| TS 32.297 vj00 | Charging Data Record File Transfer | Rel-19 |
| TS 32.298 vj30 | Charging Data Record (CDR) Parameter Specification | Rel-19 |
| TS 32.404 vj00 | Performance Management Definitions & Template | Rel-19 |
| TS 32.405 vj00 | UTRAN Performance Measurements Specification | Rel-19 |
| TS 32.406 vj00 | Performance Management for CN PS Domain | Rel-19 |
| TS 32.407 vj00 | PM; CN CS Domain; UMTS/GSM measurements | Rel-19 |
| TS 32.408 vj00 | UMTS/GSM Performance Management Measurements | Rel-19 |
| TS 32.410 vj00 | 3GPP TS 32.410: Key Performance Indicators (KPI) | Rel-19 |
| TS 32.642 vb50 | UTRAN Network Resource Model for Configuration Management | Rel-11 |
| TS 32.741 vb00 | STN Interface NRM IRP Requirements | Rel-11 |
| TS 32.808 v1800 | Common User Profile Storage Framework | Rel-8 |
| TS 32.856 vf00 | Energy Efficiency Assessment for RAN OAM | Rel-15 |
| TS 33.102 vj10 | 3G Security Architecture Specification | Rel-19 |
| TS 33.106 vj00 | Lawful Interception Requirements (Pre-Rel-15) | Rel-19 |
| TS 33.107 vj00 | Lawful Interception Architecture & Functions | Rel-19 |
| TS 33.210 vj20 | UMTS Security for IP Networks | Rel-19 |
| TS 33.812 v920 | M2M Remote Subscription Management Security | Rel-9 |
| TR 33.848 vi00 | Technical Report on Virtualisation Security | Rel-18 |
| TS 33.856 vg10 | Security for 5G to 3G Voice Continuity | Rel-16 |
| TR 33.857 vh10 | Enhanced Security for Non-Public Networks | Rel-17 |
| TS 33.859 vb10 | UTRAN Key Hierarchy Enhancement Study | Rel-11 |
| TS 36.322 vj00 | E-UTRA Radio Link Control Protocol Specification | Rel-19 |
| TS 36.331 vj00 | LTE RRC Protocol Specification | Rel-19 |
| TS 36.413 vj10 | S1 Application Protocol (S1AP) | Rel-19 |
| TS 36.785 ve00 | LTE Sidelink V2V Services Study | Rel-14 |
| TS 36.786 ve00 | TR on V2X Services based on LTE sidelink | Rel-14 |
| TS 36.787 vf00 | V2X New Band Combinations for LTE | Rel-15 |
| TS 36.843 vc01 | D2D Proximity Services Feasibility Study | Rel-12 |
| TS 36.877 vc00 | LTE Device to Device Proximity Services | Rel-12 |
| TS 36.938 v900 | E-UTRAN to 3GPP2/Mobile WiMAX Mobility | Rel-9 |
| TS 37.320 vj00 | Minimization of Drive Tests (MDT) Overview | Rel-19 |
| TS 43.055 vj00 | Dual Transfer Mode (DTM) for GSM/GPRS | Rel-19 |
| TS 43.129 vj00 | PS Handover in GERAN A/Gb and GAN Modes | Rel-19 |
| TS 43.318 vj00 | Generic Access Network (GAN) Stage 2 | Rel-19 |
| TR 43.901 vj00 | Generic Access to A/Gb Interface Feasibility Study | Rel-19 |
| TR 44.901 vj00 | Extended NACC for External Cell Change | Rel-19 |
| TR 45.913 vj00 | Optimized Transmit Pulse Shape for EGPRS2-B | Rel-19 |
| TS 48.018 vj00 | BSS-SGSN Interface for GPRS Control | Rel-19 |