Secondary Network Operator

Description

A Secondary Network Operator (SNO) is a business and operational entity defined within 3GPP's network sharing framework. The SNO does not own the radio spectrum license nor the primary Radio Access Network (RAN) infrastructure. Instead, it operates as a Mobile Virtual Network Operator (MVNO)-like entity that enters into a commercial agreement with a Primary Network Operator (PNO), also known as a Mobile Network Operator (MNO), to utilize the PNO's shared network resources to offer its own services to end-users.

Architecturally, network sharing allows multiple core network operators (each with their own core network nodes like MME, SGW, PGW in 4G, or AMF, SMF, UPF in 5G) to connect to a shared radio access network. The SNO possesses its own core network, subscriber databases (HSS/UDM), and perhaps its own service platforms. From the shared RAN's perspective, traffic from different operators' UEs is differentiated using specific network identifiers, primarily the PLMN ID. The shared RAN (e.g., eNB/gNB) is configured to broadcast the PLMN IDs of both the PNO and the SNO, and it routes user data and signaling to the respective core network based on the selected PLMN.

How it works: A subscriber with a subscription from the SNO has a SIM/USIM that is programmed with the SNO's PLMN ID. When the UE camps on the shared cell, it sees both PLMN IDs in the broadcast system information. It selects its home SNO's PLMN. The RAN, upon connection establishment, uses this selected PLMN ID to route the initial signaling message (e.g., Attach Request, Registration Request) to the core network element (e.g., MME, AMF) belonging to that specific PLMN/operator. This allows the SNO to have complete control over its subscribers' authentication, session management, and policies, while relying on the PNO for radio coverage and capacity.

Purpose & Motivation

The concept of the Secondary Network Operator was standardized to facilitate more flexible and efficient market structures in the telecommunications industry. It addresses the high barrier to entry caused by the enormous capital expenditure (CAPEX) required to acquire spectrum licenses and deploy a nationwide radio network. The SNO model enables new service providers to enter the market rapidly by leasing network capacity, fostering competition and innovation.

Its creation was motivated by regulatory pushes for increased competition and more efficient use of scarce radio spectrum and physical infrastructure (like cell sites). It solves the problem of infrastructure duplication, allowing multiple service providers to coexist without each needing to build overlapping radio networks. This is particularly valuable in scenarios like rural coverage, where a single infrastructure build-out can be shared, or for niche operators targeting specific customer segments without the burden of RAN ownership. The 3GPP specifications provide the technical enablers (like multi-PLMN RAN sharing) that make such business models operationally feasible.

Key Features

• Operates without owning licensed radio spectrum or RAN infrastructure
• Possesses its own core network nodes and subscriber management systems
• Uses a unique PLMN ID to identify its network to user equipment
• Relies on a commercial agreement with a Primary Network Operator (PNO/MNO) for RAN access
• Broadens market competition and enables new service-based market entrants
• Supported by 3GPP network sharing architectures like MORAN (Multi-Operator RAN) and MOCN (Multi-Operator Core Network)

Evolution Across Releases

Defining Specifications