Description
The Physical Termination Point (PTP) is a fundamental architectural concept within 3GPP specifications used to model the physical boundary of the network. It is not a physical device itself but a logical reference point that represents the location where a physical connection is terminated. This abstraction is essential for defining the precise endpoints of interfaces and protocols. In most contexts, the PTP is associated with the User Equipment (UE), representing the point where the user's device connects to the network's radio access or core network functions. It serves as the anchor for defining the User-Network Interface (UNI) and is critical for separating the responsibilities of the user domain from the network operator domain.
Architecturally, the PTP is used across multiple 3GPP domains, including the Core Network (CN) and Radio Access Network (RAN). In protocol stack definitions, layers are often described as providing services to higher layers at a Service Access Point (SAP), and the PTP can represent the lowest physical layer SAP. For management and charging systems, the PTP is a key identifiable point for attaching policies, measuring usage, and applying quality of service (QoS) rules. Its definition ensures consistency when specifying how information flows are initiated, terminated, and managed at the physical edge of the standardized system.
The role of the PTP extends into service definitions and network architecture diagrams. It is a stable reference that persists even as underlying technologies evolve from GSM to UMTS, LTE, and 5G NR. By providing a clear demarcation point, it aids in the specification of bearer paths, IP address allocation scenarios, and security perimeters. For instance, in the IP Multimedia Subsystem (IMS), the PTP helps define the connection point for SIP user agents. Its consistent use across dozens of 3GPP technical specifications (TS) and technical reports (TR) underscores its importance as a foundational building block for network modeling and interoperability testing.
Purpose & Motivation
The Physical Termination Point was introduced to create a clear, unambiguous, and standardized model for the physical boundary of a telecommunications network. Prior to such formal modeling, defining where the network 'ends' and the user equipment 'begins' could be imprecise, leading to potential ambiguities in interface specifications, protocol responsibilities, and service definitions. The PTP solves this by providing a universal reference point that all other architectural elements can relate to consistently.
This conceptual model is vital for the division of functional and operational responsibilities. It clearly delineates the network operator's domain from the user's domain, which is crucial for defining standardized interfaces, ensuring interoperability between equipment from different vendors, and establishing clear points for charging, lawful interception, and security enforcement. The PTP allows specifications to state definitively which functions are performed inside the network and which are performed in the user device, simplifying system design and testing.
Historically, as 3GPP systems evolved to support packet-switched services, IMS, and diverse access technologies, the need for a stable architectural anchor became even more pronounced. The PTP provides this stability, enabling new services and protocols to be integrated into the architecture by defining their relationship to this fundamental boundary point. It addresses the limitation of ad-hoc or technology-specific boundary definitions, ensuring a cohesive architectural framework from 2G to 5G and beyond.
Classification
Detected Changes Across Releases
from 3GPP Change RequestsSpecific changes extracted from the „Change history“ tables of 3GPP specifications (69 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, the PTP (Physical Termination Point) function saw specific updates related to security and physical layer procedures. This included introducing mechanisms for avoiding security risks on RLC UM bearers during a termination point change. The release also provided corrections and clarifications on procedures for BFR (Beam Failure Recovery) termination and the associated PDCCH and CFRA processes.
- Non-roaming Architecture for Network Exposure Function in reference point representation TS 23.501CR0073
- Clarification on the use of shared AMF Pointer value TS 23.501CR0289
- Coordination of reference point allocation TS 23.501CR0356
- 23.501: Reference Point and Services correction TS 23.501CR0591
- AMF Region ID (8 bits), AMF Set ID (10 bits), and AMF Pointer (6 bits) TS 24.501CR0030
- AMF pointer pointing one or more AMFs TS 24.501CR0305
+ 7 more changes
In Release 16, the PTP function was enhanced to support Time Sensitive Communication through the addition of new reference points in the architecture. Furthermore, specific support for 5GS BMCA and PTP port state configuration was introduced. These updates were part of broader enhancements to QoS handling and the clarification of reference points for various access types, including wireline.
- Architecture and reference points for Wireline AN TS 23.501CR0863
- Add new Reference points TS 23.501CR1205
- Enhancements to QoS Handling for V2X Communication Over Uu Reference Point TS 23.501CR1440
- Update to NEF related reference points TS 23.501CR1557
- Update to Clause 4.2.7 Reference Points TS 23.501CR1754
- Usage of Ethernet PDU Session Information to support 5G VN Group point to point Ethernet traffic TS 23.501CR2029
+ 10 more changes
In Release 17, the enhancements for the Physical Termination Point (PTP) function introduced support for multiple PTP instances within the 5GS and improved PTP instance configuration management. The release also clarified the support of the PTP Grandmaster function in the TT (Transport Terminal) and enabled Grandmaster candidate management information per PTP instance. Furthermore, it specified the control of PTP functionality in DS-TT and NW-TT and updated the procedures for forwarding (g)PTP messages in the UPF/NW-TT.
- Support for PTP in time synchronization service and BMCA TS 23.501CR2668
- Update for PTP in time synchronization service and BMCA TS 23.501CR2773
- Update of reference points for 5G ProSe TS 23.501CR2910
- Reference point AUSF - NSSAAF TS 23.501CR3095
- Support for PTP message delivery TS 24.535CR0007
- KI#1-4: Control of PTP functionality in DS-TT and NW-TT TS 23.501CR2549
+ 22 more changes
In Release 18, the PTP function was updated to clarify the shared NG-U termination point among gNBs for a Broadcast MBS session, enhancing multi-cell coordination. Furthermore, the release introduced support for the graceful termination of PDU sessions during network slice decommissioning, providing a more controlled service termination procedure.
- Reference point numbers for charging TS 23.501CR3752
- Support of graceful/gradual termination of PDU sessions during network slice decommissioning TS 23.501CR4078
- Add NWDAF services and Reference point between two NWDAFs for roaming case TS 23.501CR4428
- Clarification on reference point for hard satellite switch with resynchronization TS 38.331CR5372
- Clarification on resumption of non-SDT bearer in SDT termination TS 38.401CR0444
- Clarification shared NG-U Termination among gNBs for Broadcast MBS session TS 23.247CR0170
+ 1 more changes
In Release 19, the PTP function saw updates primarily focused on enhancing termination procedures for network slicing and subscription management, as indicated by CRs on slice replacement termination and SMF subscription termination notification. Specific refinements were made to notification mechanisms and reference points, including corrections to the N6 termination indication and the notification URI used for termination alerts. These changes improved the reliability and clarity of termination signaling within the core network architecture.
- Reference Points and SBIs for Ambient IoT TS 23.501CR6216
- On the termination of slice replacement TS 23.501CR6192
- Update on SMF subscription termination notification to the EIF TS 23.501CR6481
- Correction on notification URI used for termination Notification TS 29.565CR0140
- Corrections on the N6 termination indication TS 29.565CR0159
Explore further
Broader topics and technologies where PTP plays a role.
Defining Specifications
3GPP specifications that define or reference PTP, 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 22.060 vj00 | GPRS Stage 1 Service Description | Rel-19 |
| TR 22.804 vg30 | 5G Automation in Vertical Domains Study | Rel-16 |
| TR 22.867 vi20 | Study on 5G Smart Energy and Infrastructure | Rel-18 |
| TS 23.060 vj00 | GPRS Service Description Stage 2 | Rel-19 |
| TS 23.247 vj30 | 5G Multicast/Broadcast Service Architecture | Rel-19 |
| TS 23.501 vk00 | 5G System Architecture Stage 2 | Rel-20 |
| TS 23.782 vf00 | Interworking between LTE MC and non-LTE MC systems | Rel-15 |
| TS 24.065 v1310 | GPRS Subnetwork Dependent Convergence Protocol | Rel-4 |
| TS 24.501 vj50 | 5G NAS Protocols Specification | Rel-19 |
| TS 24.535 vj00 | TS 24535: (g)PTP Message Delivery Protocol | Rel-19 |
| TS 25.401 vj00 | UTRAN Overall Architecture | Rel-19 |
| TS 25.413 vj00 | Radio Access Network Application Part (RANAP) | Rel-19 |
| TS 25.420 vj00 | Iur Interface Introduction for UTRAN | Rel-19 |
| TS 25.423 vj00 | UTRAN RNSAP Specification | Rel-19 |
| TR 25.931 vj00 | UTRAN Signalling Procedures Examples | Rel-19 |
| TS 26.346 vj20 | MBMS User Services Media Codecs & Protocols | Rel-19 |
| TS 26.522 vj30 | RTP for XR in 5G Systems | Rel-19 |
| TR 26.805 vh01 | Study on Media Production over 5G NPN Systems | Rel-17 |
| TR 26.806 vi00 | Technical Report on Smartly Tethering AR Glasses | Rel-18 |
| TS 26.822 vj20 | 5G RTP Configurations Study Phase 2 | Rel-19 |
| TR 26.917 vj00 | TV Service Enhancements over 3GPP | Rel-19 |
| TR 26.946 vj00 | MBMS User Services Overview | Rel-19 |
| TS 27.060 vj00 | TE-MT Interworking for Packet Domain | Rel-19 |
| TS 29.244 vj40 | PFCP Specification for Control/User Plane Separation | Rel-19 |
| TS 29.565 vj40 | Time Synchronization Function Services | Rel-19 |
| TS 32.854 vb10 | FMC Federated Network Information Model | Rel-11 |
| TR 33.851 vh10 | Security for Industrial IoT in 5G | Rel-17 |
| TS 37.480 vj00 | E1 Interface General Aspects and Principles | Rel-19 |
| TS 37.483 vj10 | E1 Application Protocol (E1AP) | Rel-19 |
| TS 38.300 vj00 | NG-RAN Overall Description | Rel-19 |
| TS 38.321 vj00 | NR MAC Protocol Specification | Rel-19 |
| TS 38.331 vj00 | NR Radio Resource Control (RRC) Protocol Specification | Rel-19 |
| TS 38.401 vj10 | NG-RAN Architecture Specification | Rel-19 |
| TS 38.410 vj10 | NG Interface Introduction for NG-RAN to 5GC | Rel-19 |
| TS 38.413 vj10 | NG Application Protocol (NGAP) | Rel-19 |
| TS 38.470 vj10 | F1 Interface Introduction | Rel-19 |
| TS 38.473 vj10 | 5G F1 Application Protocol (F1AP) | Rel-19 |
| TS 38.807 vg10 | NR beyond 52.6 GHz Study | Rel-16 |
| TR 38.808 vh00 | Study on NR above 52.6 GHz to 71 GHz | Rel-17 |
| TR 38.825 vg00 | Study on NR Industrial IoT | Rel-16 |
| TS 44.065 vj00 | GPRS SNDCP Specification | Rel-19 |