Description
The Minimum Set of emergency related Data (MSD) is a critical 3GPP concept designed to guarantee that essential information is available to support emergency services (e.g., calling 112, 911). It is defined as the bare minimum data set that a network must be able to retrieve and utilize to establish an emergency session and provide aid, particularly for users who are not authenticated, have no valid subscription, or are roaming outside their home network. The MSD ensures that regulatory requirements for emergency services can be met under virtually all circumstances.
Architecturally, the MSD involves multiple network entities. When a User Equipment (UE) initiates an emergency request, the serving network (Visited Public Land Mobile Network - VPLMN) must attempt to acquire the MSD. This data may be stored in the UE itself, retrieved from the UE's home network (HPLMN) if possible, or derived from the network's own context. Key components involved include the UE, the Radio Access Network (RAN), the Mobility Management Entity (MME) in LTE or the Access and Mobility Management Function (AMF) in 5GC, the Gateway Mobile Location Centre (GMLC), and the Emergency Centre. The MSD typically includes, but is not limited to, the location of the UE (or information to determine it), a callback number, and the identity of the serving cell.
The process works as follows: Upon detecting an emergency service request, the network bypasses normal authentication and subscription checks. It then activates procedures to collect the MSD. The UE may provide some data (e.g., its last known location estimate if it has positioning capabilities). The network uses cell-ID or more advanced methods to determine location. A temporary identifier or a network-assigned callback number is established. This MSD is then made available to the Public Safety Answering Point (PSAP) or emergency center. The role of the MSD is to fulfill the fundamental principle that emergency services must be accessible to anyone, anytime. Its specification across numerous technical documents (from core network protocols to radio performance specs) ensures interoperability and defines fallback mechanisms for when full subscriber data is unavailable.
Purpose & Motivation
The MSD exists to solve a fundamental life-saving problem: ensuring emergency services can receive a call and locate the caller even when the cellular system lacks normal subscriber credentials. Prior to its formalization, networks might reject emergency attempts from non-subscribers or fail to provide crucial location data, potentially with fatal consequences. The MSD was motivated by regulatory and ethical mandates for universal access to emergency services.
It addresses the limitations of traditional cellular operation, which is heavily based on authenticated subscribers with known profiles. In situations like a user without a SIM card, an invalid subscription, or a roaming user whose home network is unreachable, the network still has a legal obligation to connect the emergency call. The MSD provides a standardized fallback framework. Historical context includes the evolution of emergency service requirements from basic voice connectivity (e.g., GSM Phase 1) to enhanced mandates for caller location (E911 in the US, eCall in Europe), which necessitated a robust, standardized data set.
The creation of the MSD ensures technological compliance with these regulations across all 3GPP-based networks. It defines a clear contractual point between network operators and authorities on what minimum information will be supplied. This solves interoperability issues between different network vendors and across borders, ensuring that a phone from any manufacturer, on any compliant network, can provide a baseline level of emergency support. It is a cornerstone for citizen safety in mobile communications.
Classification
Detected Changes Across Releases
from 3GPP Change RequestsSpecific changes extracted from the „Change history“ tables of 3GPP specifications (51 CRs across 5 releases). Complements the general historical overview above with the evidence-based evolution of this function.
Studied in Rel-7, normative work from Rel-15.
In Release 15, the MSD function was enhanced to ensure the delivery of local emergency numbers via the Non-Access Stratum (NAS) to the UE. This provided a standardized method for UEs to obtain the necessary emergency number list for initiating emergency calls. The release also included corrections and clarifications on the validity and usage of this emergency number list.
- Support of IMS Emergency Calls for NG-RAN access to 5GS TS 23.167CR0319
- PS to CS SRVCC for IMS emergency session in early dialogue phase TS 23.237CR0504
- Clarify that the newly introduced Extended Local Emergency Number List does not apply to the CS domain TS 24.008CR3128
- More Flexible Domain selection for Emergency Calls using the PS Domain TS 23.167CR0341
- SRVCC HO failure for Emergency handling TS 23.216CR0344
- Emergency services over 5GC via untrusted non-3GPP access TS 23.167CR0320
+ 20 more changes
In Release 16, the MSD function was enhanced to support IMS emergency sessions for roaming users in 5GS deployments without IMS-level roaming interfaces and to enable emergency calls using trusted non-3GPP access to the 5G Core. Furthermore, the release introduced procedures for 5G-SRVCC from NG-RAN to UTRAN for emergency sessions and enabled SRVCC for emergency calls transferred to EPS.
- Introduction of support of multiple EATF instances in Emergency SRVCC procedures TS 23.237CR0509
- 5G-SRVCC from NG-RAN to UTRAN for emergency session TS 23.216CR0358
- Enabling emergency call using trusted non-3GPP access to 5GC TS 23.167CR0344
- Support of IMS emergency sessions for roaming users in 5GS deployments without IMS-level roaming interfaces TS 23.167CR0350
- SRVCC operation impossible indication for 5G emergency SRVCC TS 23.216CR0367
- No retry in 4G for PDP type related SM causes TS 24.008CR3227
+ 3 more changes
In Release 17, the MSD function was enhanced to support IMS emergency calls over new access types, specifically NR satellite access and SNPNs. It also introduced new capabilities for emergency service related fallback, identified as 'CellSelection_EmergencyFallback', and added support for using an alternate P-CSCF for emergency registration. Furthermore, the release included support for signed caller identity attestation specifically for emergency IMS sessions.
- Support for Caller Identity Attestation and Assertion of Emergency sessions TS 23.167CR0359
- Support of IMS Emergency Calls over NR Satellite Access TS 23.167CR0361
- EDC related PCO parameters TS 24.008CR3295
- Support for signed attestation for emergency and priority IMS sessions TS 29.165CR1029
- KI#3: Support for IMS emergency over SNPN TS 23.167CR0360
- Introduction of capabilities for emergency service related fallback [CellSelection_EmergencyFallback] TS 38.306CR0822
+ 5 more changes
In Release 18, the MSD function was updated with a clarification to the lower MSD capability for UEs. Furthermore, a new UE capability was introduced to support barring exemption for emergency calls, ensuring these calls can be prioritized. These enhancements build upon the existing framework where a UE may camp on an acceptable cell to make emergency calls.
- Introduction of a UE capability for the barring exemption for emergency call [EM_Call_Exemption] TS 38.306CR1148
- Correction in the optionality of NR-U related information TS 38.306CR1221
- Clarification to lower MSD capability TS 38.306CR1240
- Corrections to UE capabilities related to Rel-17 URLLC and RedCap TS 38.306CR1150
In Release 19, a correction was made to the MSD function to specify the correct uplink transmission bandwidth symbol, referred to as LCRB, within the MSD data tables. This update ensures accurate parameter definitions for emergency-related data transmissions. The change addresses technical details for the uplink channel to maintain consistency in emergency service procedures.
- (NR_CADC_SUL_R19-Core) CR to 38.719-03-01 to correct UL transmission bandwidth symbol LCRB in MSD tables TS 38.719CR0001
Explore further
Broader topics and technologies where MSD plays a role.
Defining Specifications
3GPP specifications that define or reference MSD, 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 22.967 vj00 | eCall Emergency Data Transmission | Rel-19 |
| TS 23.167 vj11 | IMS Emergency Sessions | Rel-19 |
| TS 23.216 vj00 | SRVCC Architecture Enhancements | Rel-19 |
| TS 23.237 vj00 | IMS Service Continuity (ISC) Stage 2 | Rel-19 |
| TS 24.008 vj50 | 3GPP TS 24008: Core Network Protocols | Rel-19 |
| TS 24.229 vj50 | IMS call control protocol based on SIP and SDP | Rel-19 |
| TS 26.267 vj00 | eCall In-band Modem Specification | Rel-19 |
| TS 26.268 vj00 | eCall In-band Modem ANSI-C Code | Rel-19 |
| TS 26.269 vj00 | eCall In-band Modem Conformance Testing | Rel-19 |
| TR 26.967 vj00 | eCall via CTM Suitability Analysis | Rel-19 |
| TR 26.969 vj00 | eCall In-band Modem Performance Characterization | Rel-19 |
| TS 29.165 vj10 | Inter-IMS Network to Network Interface (NNI) | Rel-19 |
| TS 36.101 vj30 | LTE UE Radio Transmission & Reception Requirements | Rel-19 |
| TS 36.833 | 3GPP TR 36.833 | Rel-7 |
| TS 36.853 | 3GPP TR 36.853 | Rel-7 |
| TS 37.716 | 3GPP TR 37.716 | Rel-7 |
| TS 37.717 | 3GPP TR 37.717 | Rel-7 |
| TS 37.718 | 3GPP TR 37.718 | Rel-7 |
| TS 37.719 vj00 | 3GPP TR 37.719: Dual Connectivity Band Combinations | Rel-19 |
| TS 37.825 vg00 | High Power UE (PC2) for EN-DC TDD-TDD | Rel-16 |
| TS 37.863 | 3GPP TR 37.863 | Rel-7 |
| TS 37.864 | 3GPP TR 37.864 | Rel-7 |
| TS 37.865 | 3GPP TR 37.865 | Rel-7 |
| TS 37.866 | 3GPP TR 37.866 | Rel-7 |
| TS 37.872 vf10 | Technical Report on SUL & LTE-NR DC with SUL | Rel-15 |
| TR 37.878 vi00 | Technical Report on Rel-18 NR V2X Band Combinations | Rel-18 |
| TS 37.898 vj00 | Rel-19 HPUE for EN-DC Band Combinations | Rel-19 |
| TS 38.101 vj31 | NR User Equipment Radio Transmissions | Rel-19 |
| TS 38.306 vj00 | NR UE Radio Access Capability Parameters | Rel-19 |
| TS 38.521 vj20 | NR Physical Layer UE Conformance Testing | Rel-19 |
| TS 38.716 | 3GPP TR 38.716 | Rel-7 |
| TS 38.717 | 3GPP TR 38.717 | Rel-7 |
| TS 38.718 | 3GPP TR 38.718 | Rel-7 |
| TS 38.719 vj00 | Rel-19 NR SUL Configurations and CA Band Combinations | Rel-19 |
| TS 38.741 vj00 | NTN L-/S-band for NR Technical Specification | Rel-19 |
| TS 38.746 vj00 | High Power UE for NR Inter-band CA/DC | Rel-19 |
| TS 38.750 vj00 | High Power UE for NR Inter-band CA/DC | Rel-19 |
| TS 38.755 vj10 | NR FR1 DL Fragmented Carriers Study | Rel-19 |
| TS 38.792 vj00 | UE RF Requirements for PC1.5 Inter-band UL CA/DC | Rel-19 |
| TS 38.793 vj00 | Simultaneous Rx/Tx Band Combinations TR | Rel-19 |
| TS 38.796 vj00 | Rel-19 High Power UE for NR FR1 | Rel-19 |
| TR 38.839 vh00 | Simultaneous Rx/Tx band combinations | Rel-17 |
| TR 38.841 vh00 | High power UE for NR inter-band CA | Rel-17 |
| TR 38.842 vh00 | High Power UE for NR CA with Multiple Bands | Rel-17 |
| TR 38.846 vi10 | Technical Report | Rel-18 |
| TR 38.850 vi10 | Technical Report for Rel-18 High Power UE | Rel-18 |
| TS 38.863 vj10 | NR NTN RF and Co-existence Spec | Rel-19 |
| TS 38.870 vj20 | Enhanced OTA Test Methods for NR FR1 TRP/TRS | Rel-19 |
| TR 38.872 vi40 | Technical Report on Sub-1GHz NR Band Combinations | Rel-18 |
| TR 38.880 vi00 | Technical Report for 3Tx inter-band UL CA and EN-DC | Rel-18 |
| TR 38.881 vi00 | Technical Report on Lower MSD for Inter-band CA/EN-DC/DC | Rel-18 |
| TR 38.894 vi00 | Technical Report | Rel-18 |
| TR 38.896 vi00 | Technical Report for High Power UE (Power Class 2) for NR FR1 FDD | Rel-18 |
| TR 38.899 vi00 | Technical Report for High Power UE | Rel-18 |