Description
Mobile Originated (MO) Short Message Service is a standardized mechanism for a User Equipment (UE) to initiate and transmit a short text message to a recipient via the mobile network. The process begins when the user composes and sends an SMS from the device. The UE packages the message, including the destination address (typically an MSISDN) and the text content, into a CP-DATA message as per the protocol defined in 3GPP TS 24.011. This message is sent over the signaling channels (e.g., using the Connection Management (CM) sublayer) to the Mobile Switching Centre (MSC) in circuit-switched networks or the Mobility Management Entity (MME)/Access and Mobility Management Function (AMF) in packet-switched networks for SMS over IP.
The MSC or MME/AMF, upon receiving the MO-SMS, forwards it to the Interworking MSC (IWMSC) or the IP-SM-GW, which acts as a gateway to the Short Message Service Centre (SMSC). The SMSC is the central hub responsible for store-and-forward functionality. It receives the MO message, stores it, and then initiates the Mobile Terminated (MT) process to deliver it to the intended recipient. The delivery involves querying the Home Location Register (HLR) or Home Subscriber Server (HSS) to determine the recipient's current serving network node.
Key architectural components involved in MO-SMS include the UE (with its SMS application and protocol stack), the radio access network (RAN) for transmission, the core network control plane nodes (MSC, MME, AMF, SMSC), and the necessary interfaces (e.g., the air interface, the interface to the SMSC). The service operates on the control plane, ensuring delivery even when no user-plane bearer is established, which is crucial for reliability. MO-SMS supports both circuit-switched (CS) and packet-switched (PS) domains, with evolution towards SMS over IP (IMS) as defined in later releases.
The role of MO-SMS in the network is foundational for text-based communication. It leverages existing signaling infrastructure, making it a low-bandwidth, highly reliable service. Its integration into the core network ensures widespread interoperability and forms the basis for value-added services like SMS-based authentication, notifications, and machine-to-machine (M2M) communication. The protocols ensure error handling, delivery reports, and concatenation for longer messages.
Purpose & Motivation
MO-SMS was created to provide a simple, efficient, and ubiquitous text messaging service for mobile subscribers. Prior to SMS, mobile communication was primarily voice-centric. The development of SMS, including the MO capability, leveraged unused capacity in the signaling channels of GSM networks (specifically the Stand-alone Dedicated Control Channel - SDCCH), allowing text messages to be sent without requiring a dedicated voice channel. This was a revolutionary, cost-effective way to enable asynchronous communication.
The technology solved the problem of enabling brief, non-voice communication between users and between networks and devices. It addressed the need for a reliable, store-and-forward messaging system that could work across different network operators and regions. Its creation was motivated by the desire to utilize network resources more efficiently and to open a new revenue stream and service offering for operators.
Over time, MO-SMS became the backbone for numerous applications beyond person-to-person messaging, including service activation, banking alerts, and two-factor authentication, due to its high reliability and nearly universal reach. It established the foundational architecture and protocols for mobile-originated data services that later evolved to support more complex messaging and IoT scenarios.
Classification
Detected Changes Across Releases
from 3GPP Change RequestsSpecific changes extracted from the „Change history“ tables of 3GPP specifications (118 CRs across 5 releases). Complements the general historical overview above with the evidence-based evolution of this function.
In Release 15, new Mobile Originated (MO) capabilities were introduced for handling emergency registration timers and for scenarios where Voice over Packet-Switched (VoPS) service is not supported. The release also specified MO procedures for authorizing remotely initiated calls via user profile updates and for enabling 3GPP PS data off in roaming configurations. Furthermore, updates were made to the Management Object (MO) for provisioning ProSe Direct Services over WLAN for Direct Discovery.
- Adding 5GS NAS messages to clause 11 TS 24.008CR3132
- MO on registration handling when VoPS not supported TS 24.167CR0192
- MO for emergency registration timer TS 24.167CR0210
- Update to ProSe Direct Services Provisioning MO for WLAN Direct Discovery TS 24.333CR0060
- Enabling 3GPP PS data off in roaming-NAS MO TS 24.368CR0033
- MO for service type and Tx profile mapping rules TS 24.385CR0013
+ 25 more changes
In Release 16, new Mobile Originated (MO) capabilities were introduced for 5G Core, including Mobile Originated Data Transfer for Control Plane CIoT 5GS Optimisation and MO Exception Data Delivery for both CP and UP CIoT. The release also specified MO functions for restricting incoming private and MCData communications, and included the new MessageStoreHostname element. Furthermore, updates were made for V2X communications over the NR-PC5 interface and for handling NAS Session Management retry procedures.
- V2X MO update for V2X over NR-PC5 TS 24.385CR0021
- Restricting incoming private communications MO TS 24.483CR0057
- MO for limiting the number of emergency group calls for a specific functional alias TS 24.483CR0058
- Included the MessageStoreHostname element TS 24.483CR0077
- Included the MessageStoreHostname element TS 24.484CR0141
- Mobile Originated Data Transfer for Control Plane CIoT 5GS Optimisation TS 29.502CR0228
+ 18 more changes
In Release 17, the MO function was enhanced with new configurations for Standalone Non-Public Networks (SNPN) in both IMS and XCAP contexts, and with updates to support allowed Feature Authorizations (FAs) for services like MCData and MCVideo. It also introduced configurations for functional alias association with groups, user control over communications storage into a message store, and an MO annex for 5GS/EPS terminology alignment. Furthermore, specific updates were made for V2X communications over NR-PC5 in EPC and for 5GS QoS aspects within the MO configuration.
- SNPN configuration in IMS MO TS 24.167CR0225
- SNPN configuration in XCAP MO TS 24.424CR0013
- Add PreconfiguredGroupUseOnly MO TS 24.483CR0080
- MO update to support allowed FAs TS 24.483CR0098
- MO for limiting the number of MCData emergency groups per FA TS 24.483CR0099
- Functional alias association with group – MO configurations TS 24.483CR0136
+ 27 more changes
In Release 18, enhancements for the Mobile Originated (MO) function included the introduction of a V2X MO for the NR eTx profile to enable V2X communication over the NR-PC5 interface, alongside specific MO configurations for IMS Data Channel setup and for utilizing the SENSE feature. Additionally, updates were made to clarify MO SMS fallback procedures and to align MO SM delivery application error codes.
- MO SM delivery application error codes alignment TS 23.540CR0009
- MO configuration for IMS DC setup TS 24.275CR0005
- NAS configuration MO for using SENSE TS 24.368CR0065
- Introducing V2X MO for the NR eTx profile for V2X communication over NR-PC5 in EPC TS 24.385CR0030
- MO for MCS over 5G ProSe TS 24.483CR0163
- Support of Mobile Base Station Relay in SMF services TS 29.502CR0678
+ 10 more changes
In Release 19, the MO (Mobile Originated) function was enhanced with new configuration capabilities for multi-talker and emergency remote floor request authorization, as well as the addition of an LMS URI in the MCS UE initial configuration. Furthermore, specific MO configurations were introduced for LCS services, including a new LCS-UPP MO for PS data off and the addition of an Idm client id MO. These updates expanded the procedural and service capabilities for mobile-originated communications and location services.
- NAS MO Lower Selection-priority for PLMN Selection TS 24.368CR0087
- Addition of LMS URI in MCS UE initial configuration MO TS 24.483CR0186
- Multi-talker MO configuration TS 24.483CR0187
- Emergency remote floor request authorization MO configuration TS 24.483CR0190
- Add message flows of converged charging for UE positioning assisted by Sidelink Positioning and involving 5GC TS 32.271CR0022
- Add message flows of converged charging for Ranging and Sidelink Positioning service exposure TS 32.271CR0024
+ 8 more changes
Explore further
Broader topics and technologies where MO plays a role.
Defining Specifications
3GPP specifications that define or reference MO, 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 |
| TR 21.978 v1300 | CAMEL Control of VoIP Services Feasibility Study | Rel-4 |
| TS 22.031 vj00 | Fraud Information Gathering System (FIGS) Stage 1 | Rel-19 |
| TS 22.034 vj00 | High Speed Circuit Switched Data (HSCSD) Stage 1 | Rel-19 |
| TS 22.101 vk00 | Service Principles for PLMNs | Rel-20 |
| TS 22.105 vj00 | Telecommunication Services Framework | Rel-19 |
| TS 23.018 vj00 | Basic call handling in 3GPP CS domain | Rel-19 |
| TS 23.031 vj00 | Fraud Information Gathering System (FIGS) - Stage 2 | Rel-19 |
| TS 23.035 vj00 | Immediate Service Termination (IST) Stage 2 | Rel-19 |
| TS 23.078 vj00 | CAMEL Phase 4 Stage 2 Specification | Rel-19 |
| TS 23.107 vj00 | UMTS QoS Framework | Rel-19 |
| TS 23.207 vj00 | End-to-End QoS Framework for GPRS | Rel-19 |
| TS 23.218 vj00 | IMS Call Model Specification | Rel-19 |
| TS 23.278 vj00 | CAMEL for IMS Stage 2 Specification | Rel-19 |
| TS 23.540 vj20 | 5G Service Based SMS Stage 2 | Rel-19 |
| TS 23.725 vg20 | Study on URLLC Architecture Enhancements | Rel-16 |
| TS 23.887 vc00 | Architectural enhancements for MTC and mobile data | Rel-12 |
| TS 24.008 vj50 | 3GPP TS 24008: Core Network Protocols | Rel-19 |
| TS 24.116 vj00 | Stage 3 for Broadcast TV Service Architecture | Rel-19 |
| TS 24.117 vj00 | TV Service Configuration Management Object | Rel-19 |
| TS 24.166 vj00 | IMS Conferencing Management Object | Rel-19 |
| TS 24.167 vj00 | 3GPP IMS Management Object Specification | Rel-19 |
| TS 24.175 vj00 | Multi-Device and Multi-Identity in IMS Management Object | Rel-19 |
| TS 24.216 vj00 | Communication Continuity Management Object | Rel-19 |
| TS 24.235 vc10 | I-WLAN Interworking Management Object | Rel-12 |
| TS 24.275 vj00 | MO for MMTEL Basic Communication Part | Rel-19 |
| TS 24.285 vj00 | Allowed CSG List Management Object | Rel-19 |
| TS 24.286 vj00 | 3GPP TS 24.286: ICS Management Object | Rel-19 |
| TS 24.302 vj00 | Access to EPC via non-3GPP networks; Stage 3 | Rel-19 |
| TS 24.305 vj00 | Selective Disabling of 3GPP UE Capabilities | Rel-19 |
| TS 24.312 vj00 | ANDSF Management Objects Specification | Rel-19 |
| TS 24.323 vj00 | IMS Service Level Tracing Management Object | Rel-19 |
| TS 24.333 vj00 | ProSe Management Objects for UE Configuration | Rel-19 |
| TS 24.368 vj40 | NAS Configuration Management Object | Rel-19 |
| TS 24.385 vj00 | V2X Communication Provisioning Management Object | Rel-19 |
| TS 24.391 vj00 | USSD over IMS Management Object Specification | Rel-19 |
| TS 24.417 vj00 | OIP/OIR Management Object Specification | Rel-19 |
| TS 24.424 vj00 | XCAP over Ut for Supplementary Services MO | Rel-19 |
| TS 24.483 vj20 | Mission Critical Services Management Object | Rel-19 |
| TS 24.484 vj30 | MCS Configuration Management | Rel-19 |
| TS 25.222 vj00 | UTRA TDD Multiplexing & Channel Coding | Rel-19 |
| TS 26.114 vj10 | IMS Multimedia Telephony Media Handling | Rel-19 |
| TS 26.130 vj00 | RTP Payload Format Testing for 3GPP Codecs | Rel-19 |
| TS 26.238 vj00 | Framework for Live Uplink Streaming (FLUS) | Rel-19 |
| TS 26.849 vc10 | MBMS Operation on Demand (MooD) | Rel-12 |
| TS 28.510 vj00 | NFV Configuration Management Requirements | Rel-19 |
| TS 28.606 vc10 | CN and non-3GPP interworking NRM IRP Solution Sets | Rel-12 |
| TS 28.616 vj00 | EPC and non-3GPP access NRM IRP SS definitions | Rel-19 |
| TS 28.622 vk20 | Telecommunication Management; Generic NRM Information Service | Rel-20 |
| TS 28.629 vj00 | SON Policy NRM IRP Solution Set Definitions | Rel-19 |
| TS 28.632 vj00 | Inventory Management NRM Integration Reference Point | Rel-19 |
| TS 28.652 vj00 | UTRAN Network Resource Model (NRM) IRP Information Service | Rel-19 |
| TS 28.653 vj00 | UTRAN NRM IRP Solution Set Definition | Rel-19 |
| TS 28.656 vj00 | GERAN NRM IRP Solution Set Definitions | Rel-19 |
| TS 28.659 vj00 | E-UTRAN NRM IRP Solution Set Definitions | Rel-19 |
| TS 28.663 vj00 | Generic RAN NRM IRP Solution Set Definitions | Rel-19 |
| TS 28.673 vj00 | HNS NRM IRP Solution Set Definitions | Rel-19 |
| TS 28.676 vj00 | HeNS NRM IRP Solution Set Definitions | Rel-19 |
| TS 28.702 vj00 | Core Network NRM IRP Information Service | Rel-19 |
| TS 28.703 vj00 | Core Network NRM IRP Solution Set Definitions | Rel-19 |
| TS 28.705 vj00 | IMS NRM IRP Information Service | Rel-19 |
| TS 28.706 vj00 | IMS NRM IRP Solution Set definitions | Rel-19 |
| TS 28.708 vj00 | EPC NRM Integration Reference Point Information Service | Rel-19 |
| TS 28.709 vj00 | EPC NRM IRP Solution Set Definitions | Rel-19 |
| TS 28.733 vj00 | TN NRM IRP Solution Set Definitions | Rel-19 |
| TS 28.735 vj00 | STN Interface NRM IRP Information Service | Rel-19 |
| TS 28.736 vj00 | STN Interface NRM IRP Solution Set Definitions | Rel-19 |
| TR 28.816 vh00 | Charging for 5G Cellular IoT | Rel-17 |
| TS 29.078 vj00 | CAMEL Phase 4 CAP Specification | Rel-19 |
| TS 29.502 vj50 | 5G System; Nsmf Service Based Interface; Stage 3 | Rel-19 |
| TS 29.541 vj30 | NEF Service-Based Interfaces for NIDD & SMS | Rel-19 |
| TS 32.111 vj00 | Fault Management Requirements | Rel-19 |
| TS 32.153 vj00 | IRP Technology-Specific Templates Specification | Rel-19 |
| TS 32.240 vj40 | Charging Management Architecture & Principles | Rel-19 |
| TS 32.251 vj00 | PS Domain Charging Management | Rel-19 |
| TS 32.270 vj00 | MMS Charging Management Specification | Rel-19 |
| TS 32.271 vj20 | 3GPP LCS Charging Management Spec | Rel-19 |
| TS 32.272 vj00 | Charging for Push-to-Talk over Cellular (PoC) | Rel-19 |
| TS 32.276 vj00 | VCS Online Charging from Proxy Function | Rel-19 |
| TS 32.293 vj00 | Proxy Function in Domestic Service Provider | Rel-19 |
| TS 32.300 vj00 | 3GPP Network Resource Naming Convention | Rel-19 |
| TS 32.523 v930 | SON Policy NRM IRP CORBA Solution Set | Rel-9 |
| TS 32.526 vb70 | SON Policy NRM IRP Solution Set definitions | Rel-11 |
| TS 32.602 vj00 | Basic Configuration Management IRP Information Service | Rel-19 |
| TS 32.603 v910 | Basic CM IRP CORBA Solution Set | Rel-9 |
| TS 32.606 vj00 | Basic CM IRP Solution Set for CORBA/SOAP | Rel-19 |
| TS 32.607 v1910 | CM IRP SOAP Solution Set Mapping | Rel-9 |
| TS 32.612 vj00 | Bulk Configuration Management IRP: Information Service | Rel-19 |
| TS 32.613 v1910 | Bulk CM IRP CORBA Solution Set | Rel-9 |
| TS 32.616 vj00 | Bulk CM IRP Solution Set Definitions | Rel-19 |
| TS 32.622 vb10 | Generic Network Resources IRP NRM | Rel-11 |
| TS 32.623 v900 | Generic NRM CORBA Solution Set | Rel-9 |
| TS 32.626 vb20 | Generic Network Resources IRP Solution Set Definitions | Rel-11 |
| TS 32.632 vb00 | Core Network Resources IRP: Network Resource Model | Rel-11 |
| TS 32.633 v1920 | Core Network Resources IRP CORBA Mapping | Rel-9 |
| TS 32.636 vb00 | CM Core Network Resources IRP Solution Set | Rel-11 |
| TS 32.641 vb00 | UTRAN Network Resources IRP Requirements | Rel-11 |
| TS 32.642 vb50 | UTRAN Network Resource Model for Configuration Management | Rel-11 |
| TS 32.643 v930 | UTRAN Network Resources IRP: CORBA Solution Set | Rel-9 |
| TS 32.646 vc00 | UTRAN NRM IRP Solution Set Definitions | Rel-12 |
| TS 32.651 vb00 | GERAN Network Resources CM IRP Requirements | Rel-11 |
| TS 32.652 vc00 | GERAN Network Resources NRM for Configuration Management | Rel-12 |
| TS 32.653 v920 | GERAN Network Resources IRP CORBA Solution Set | Rel-9 |
| TS 32.656 vc00 | GERAN NRM IRP Solution Set Definitions | Rel-12 |
| TS 32.662 vj00 | Configuration Management (CM); Kernel CM IRP | Rel-19 |
| TS 32.663 v1900 | Kernel CM IRP CORBA Mapping | Rel-9 |
| TS 32.666 vj00 | Kernel CM IRP Solution Set Definitions | Rel-19 |
| TS 32.667 v1900 | Kernel CM IRP SOAP Solution Set | Rel-9 |
| TS 32.692 vb00 | Inventory Management NRM IRP Specification | Rel-11 |
| TS 32.712 vb10 | Transport Network Interface NRM for CM | Rel-11 |
| TS 32.713 v900 | TN Interface NRM IRP: CORBA Solution Set | Rel-9 |
| TS 32.716 vb00 | TN NRM IRP Solution Set Definitions | Rel-11 |
| TS 32.721 vb00 | Repeater Network Resources IRP Requirements | Rel-11 |
| TS 32.722 vb00 | Repeater NRM IRP: Network Resource Model | Rel-11 |
| TS 32.723 v900 | Repeater NRM CORBA Solution Set | Rel-9 |
| TS 32.726 vb00 | Repeater NRM IRP Solution Set Definitions | Rel-11 |
| TS 32.732 vb00 | IMS Network Resource Model IRP: Information Service | Rel-11 |
| TS 32.733 v910 | IMS NRM IRP CORBA Solution Set | Rel-9 |
| TS 32.736 vb00 | IMS NRM IRP Solution Set Definitions | Rel-11 |
| TS 32.741 vb00 | STN Interface NRM IRP Requirements | Rel-11 |
| TS 32.742 vb00 | STN NRM for Configuration Management | Rel-11 |
| TS 32.743 v1900 | CORBA Solution Set for STN IRP | Rel-9 |
| TS 32.746 vb00 | STN NRM IRP Solution Set Definitions | Rel-11 |
| TS 32.752 vb01 | EPC NRM IRP Information Service | Rel-11 |
| TS 32.753 v920 | EPC NRM IRP CORBA Solution Set | Rel-9 |
| TS 32.756 vb00 | EPC NRM IRP Solution Set Definitions | Rel-11 |
| TS 32.762 vb70 | E-UTRAN NRM IRP Information Service | Rel-11 |
| TS 32.763 v1950 | E-UTRAN NRM IRP CORBA Solution Set | Rel-9 |
| TS 32.766 vb90 | E-UTRAN NRM IRP Solution Set Definitions | Rel-11 |
| TS 32.773 v900 | HNS NRM IRP CORBA Solution Set | Rel-9 |
| TS 32.776 vb00 | HNS NRM IRP Solution Set Definitions | Rel-11 |
| TS 32.783 v1900 | HeNS NRM IRP CORBA Solution Set | Rel-9 |
| TS 32.786 vb00 | 3GPP TS 32.786: HeNS NRM IRP Solution Set | Rel-11 |
| TS 32.796 vc00 | Generic RAN NRM IRP Solution Set Definitions | Rel-12 |
| TS 32.818 v800 | SA5 MTOSI XML Harmonization Study | Rel-8 |
| TS 32.849 vd00 | IMS Roaming Charging Study | Rel-13 |
| TS 32.851 vc20 | Network Sharing OAM Requirements | Rel-12 |
| TS 36.331 vj00 | LTE RRC Protocol Specification | Rel-19 |
| TS 43.802 vc00 | GERAN Enhancements for Mobile Data Applications | Rel-12 |
| TR 43.901 vj00 | Generic Access to A/Gb Interface Feasibility Study | Rel-19 |