Network Subset Personalisation

Description

Network Subset Personalisation (NSP) is a 3GPP-defined mechanism that allows network operators to restrict the usage of a Mobile Equipment (ME) to a specific subset of SIM/USIMs. It is a refinement of network personalisation, which locks an ME to a single network operator. NSP provides a finer level of control, enabling operators to target specific customer segments, service tiers, or distribution channels. This is achieved through the use of a network subset code, which is stored on the SIM/USIM and checked by the ME during initialisation.

The personalisation process involves configuring the ME with a network subset code (or a group of codes) that it will accept. When a SIM/USIM is inserted, the ME reads the network subset code from the SIM/USIM and compares it with the stored value. If the code matches, or if the SIM/USIM belongs to the allowed subset, the ME operates normally. Otherwise, the ME may restrict access to services, display a message, or refuse to operate. This mechanism is defined in 3GPP TS 22.022, which specifies the personalisation categories and procedures.

NSP is part of a broader personalisation framework that includes network personalisation, service provider personalisation, corporate personalisation, and SIM/USIM personalisation. Each level provides different granularity of control. Network personalisation is the most restrictive, locking the ME to a single network. NSP relaxes this by allowing a subset of SIM/USIMs within that network. This is useful for operators who want to offer subsidised handsets that can only be used with SIM cards from a particular brand, tariff, or region, but not necessarily all SIM cards from the operator.

The technical implementation of NSP relies on the ME's ability to store and verify the network subset code. The code is typically a numeric value that is assigned by the operator and written to the SIM/USIM during personalisation. The ME, when personalised, stores the allowed code(s) in its non-volatile memory. During the SIM/USIM initialisation procedure, the ME reads the network subset code from the SIM/USIM and performs the comparison. If the ME is not personalised for network subset, it skips this check. The personalisation can be permanent or temporary, depending on the operator's policy and the ME's capabilities.

NSP has been part of 3GPP specifications since Rel-4 and has remained stable across releases. Its definition in 21.905 and 22.022 has not changed, reflecting its mature and well-understood nature. It continues to be relevant in the era of 5G and beyond, as operators still use personalisation to enforce business rules and protect subsidies. Understanding NSP is important for engineers involved in device management, SIM/USIM personalisation, and operator business support systems.

Purpose & Motivation

Network Subset Personalisation was created to address the limitations of network personalisation, which only allowed operators to lock a device to their entire network. While this was effective for preventing usage on competitor networks, it did not allow operators to differentiate between different types of customers or service offerings within their own network. NSP fills this gap by enabling operators to restrict a device to a subset of SIM/USIMs, such as those issued under a specific tariff plan, to a particular distribution channel, or to a corporate account.

The primary motivation for NSP is to support business models that rely on device subsidisation. Operators often sell handsets at a discount in exchange for a commitment from the customer to use the operator's services. Network personalisation ensures the device is used on the operator's network, but it does not prevent the customer from using a different SIM card from the same operator, such as a prepaid SIM, which might not generate the same revenue. NSP allows the operator to lock the device to a specific subset of SIM cards, ensuring that the subsidy is tied to the intended service plan.

Historically, the need for NSP arose as mobile markets became more segmented and operators sought to offer tailored packages. The 3GPP personalisation framework was developed to provide standardised mechanisms for these business needs. NSP is one of several personalisation categories, each addressing a different level of control. It provides a balance between flexibility and control, allowing operators to enforce their business rules without completely locking the device to a single SIM card. This has been particularly important in markets where prepaid and postpaid segments coexist, and where operators want to prevent arbitrage between them.