Selected Home Operator

Description

The Selected Home Operator (SHO) is a critical identifier within the 3GPP network management architecture, primarily utilized in roaming and inter-operator scenarios. It functions as a key parameter that unambiguously designates the home Public Land Mobile Network (HPLMN) of a roaming subscriber. This designation is not merely a label; it is integral to the operational and business logic of visited networks. When a User Equipment (UE) attaches to a Visited Public Land Mobile Network (VPLMN), the network elements, particularly those involved in charging and policy control, must identify the subscriber's home operator to apply the correct commercial and service agreements.

The technical implementation of SHO spans several network domains. In the charging domain, specified in 3GPP TS 32.405, the SHO is included within Charging Data Records (CDRs) generated by the Visited Network. This allows for the accurate correlation of usage data with the specific home operator for billing settlement. From a security and network access perspective, as outlined in TS 33.812, the SHO plays a role in authentication and authorization procedures, ensuring that roaming subscribers are granted access based on the agreements between the VPLMN and the identified HPLMN. The concept is also relevant in the context of network sharing and Multi-Operator Core Network (MOCN) architectures, where a single radio access network is shared by multiple core network operators.

Architecturally, the SHO is propagated through various reference points. It is typically derived from the International Mobile Subscriber Identity (IMSI) or is explicitly signaled during network attachment and session establishment procedures. Network elements like the Serving GPRS Support Node (SGSN), Mobility Management Entity (MME), or Policy and Charging Rules Function (PCRF) in the visited network use this identifier to select the appropriate Diameter routing agents or inter-operator interfaces to communicate with the home network's systems, such as the Home Subscriber Server (HSS) or Online Charging System (OCS). Its role is therefore foundational to the seamless, secure, and billable operation of global mobile roaming.

Purpose & Motivation

The Selected Home Operator concept was introduced to address the complexities of modern roaming, network sharing, and multi-operator environments. Prior to its formalization, identifying the precise home operator for a roaming subscriber could be ambiguous, especially with the rise of Mobile Virtual Network Operators (MVNOs) and complex network sharing agreements. This ambiguity posed significant challenges for accurate billing, fraud prevention, and the consistent application of service-level agreements (SLAs) between operators.

Its creation was motivated by the need for a standardized, reliable mechanism within network management and charging systems to pinpoint the responsible home operator. This is not just a technical requirement but a critical business one. Roaming revenue settlement between operators depends on precise attribution of subscriber usage. Furthermore, as regulatory frameworks evolved to mandate fair access and roaming, having a clear SHO identifier became essential for compliance, enabling visited networks to apply the correct policies for quality of service, access control, and emergency services based on the specific home operator agreement. It solves the problem of operator identification in a landscape where a subscriber's IMSI might be associated with a reseller (MVNO) rather than the underlying infrastructure provider, ensuring the business and operational chain remains clear and actionable.