Standard Communication with Network Elements

Description

Standard Communication with Network Elements (SCONE) is a Release 20 work item and architectural framework designed to standardize how external and internal applications communicate with network elements. It is specified across a set of documents including 26.804 (codec and media handling aspects), 29.122 (T8 reference point for Northbound APIs), 29.244 (Packet Forwarding Control Protocol, PFCP), 29.512 (Session Management Policy Control Service), 29.514 (Policy Authorization Service), and 29.522 (5G System Access and Mobility Policy Control Service). Collectively these specifications define service-based and reference-point interfaces through which applications can request, influence, or query network behavior in a consistent manner.

The core problem SCONE addresses is fragmentation. Historically, applications interacted with different network functions through bespoke, function-specific APIs and protocols — for example, policy requests went through the PCF via Rx or N5/Npcf, packet forwarding control through the SMF via PFCP, and media handling through dedicated interfaces. Each interface had its own data model, session semantics, and lifecycle management, forcing application developers and operators to implement and maintain many distinct integrations. SCONE introduces a harmonized communication model so that a single application or AF can interact with multiple network elements using aligned procedures, common identifiers, and consistent error handling.

The architecture leverages the 5G Service Based Architecture (SBA). Network functions expose services via HTTP/2-based RESTful APIs (the Nxxx service interfaces), and SCONE extends this paradigm to cover communication patterns that previously fell outside the SBA scope or were addressed by legacy reference points. It builds on the Policy Authorization Service (29.514), which allows an AF to create and manage application session contexts with the PCF, and on the Session Management Policy Control Service (29.512), which governs how policy decisions are translated into session-level rules. For user-plane control, PFCP in 29.244 provides the means to program forwarding behavior in UPF network elements, and SCONE aligns how applications can trigger or query such behavior.

Key components include a common session model that maps application-level requests to network-level contexts, standardized service operations (create, update, delete, notify) across the involved network functions, and unified event subscription and reporting mechanisms. This allows, for example, an application to establish a media session, request specific QoS treatment, and subscribe to notifications about session state, all through coherent interfaces. Interworking with existing 4G/5G reference points is considered so that SCONE can coexist with and gradually replace legacy integration approaches.

SCONE matters because it reduces integration complexity, accelerates service creation, and improves interoperability between applications and network elements. It supports the industry trend toward programmable, API-exposed networks where developers can consume telecom capabilities as services. By consolidating communication patterns across policy, session management, and forwarding control, SCONE lowers the barrier for vertical industries and third-party developers to leverage network capabilities reliably.

Purpose & Motivation

SCONE was created to solve the longstanding fragmentation of application-to-network communication in mobile core networks. Before SCONE, an application wanting to influence QoS, control a media session, or program user-plane forwarding had to integrate with separate, function-specific interfaces such as Rx, N5, PFCP, and T8. Each had distinct data models and lifecycle semantics, resulting in high integration cost, inconsistent behavior, and slow time-to-market for new services.

The motivation also stems from the growing need for network programmability and exposure. With 5G and beyond, operators want to offer network capabilities as consumable APIs to enterprises and developers. Fragmented interfaces undermine this goal because developers must learn and maintain many protocol variants. SCONE provides a standardized, coherent communication framework so that a single integration can reach multiple network elements with aligned procedures and data semantics.

Historically, 3GPP policy and control interfaces evolved independently across releases, and interworking between them was often handled by vendor-specific mediation. By harmonizing these interfaces under the Service Based Architecture, SCONE builds on the success of RESTful Nxxx APIs while extending coverage to elements and functions that were previously outside the SBA. This reduces the need for proprietary gateways and improves multi-vendor interoperability, which is essential for open, programmable networks.