Destination User (GPRS Called Party)

Description

The destination user is a vocabulary term defined in TS 21.905, the 3GPP glossary of terms and definitions, and used in TS 22.060, the stage 1 service description for the General Packet Radio Service (GPRS). It denotes the entity to which calls to GPRS are directed — that is, the addressed party of a GPRS service request or packet data session. The term is intentionally generic: it refers to the logical recipient of a GPRS communication rather than to a specific network node, and it is used alongside the corresponding notion of an originating user.

In GPRS, the concept of a 'call' is different from circuit-switched telephony. A GPRS communication is a packet data session, established when a mobile station activates a PDP context towards a GGSN. The destination user is the endpoint of that session: it may be a mobile subscriber, an application server, a corporate host, or any addressable entity in an external packet data network. The term therefore covers both mobile-to-mobile and mobile-to-host communications, and it is deliberately broad enough to accommodate the many addressing schemes that GPRS supports, including IPv4, IPv6 and X.121-style addressing in early releases.

Architecturally, reaching the destination user involves the SGSN, the GGSN and the external packet data network. The mobile station requests a PDP context specifying an access point name and, optionally, a destination address. The SGSN selects a GGSN based on the APN, and the GGSN allocates or validates the address, establishes the connection to the external network, and begins forwarding user-plane packets. The destination user is identified by the address carried in those packets; the GPRS core network does not need to know the internal structure of the destination, only how to route packets towards it. This separation of the GPRS bearer from the identity of the destination user is one of the defining characteristics of GPRS and a key reason for its scalability.

The term also appears in the context of GPRS supplementary and value-added services, where the destination user may be the recipient of a short message, a location request, or a push service. In all these cases the same principle applies: the destination user is the addressed entity, and the GPRS network provides the bearer that carries the communication to it. Because GPRS is a bearer service, the destination user is not necessarily a human subscriber; it can be a machine or an application, which is why the term is phrased as 'user' rather than 'subscriber'.

For engineers and students, the destination user concept is a useful reminder that GPRS is a packet-switched bearer with an addressing model inherited from the data networking world, not a circuit-switched service with a fixed called-party number. Understanding who the destination user is — and how the network resolves the address to a route — is fundamental to troubleshooting PDP context activation failures, APN resolution problems, and interworking between the mobile network and external packet data networks. The definition has remained stable from Rel-4 through Rel-19, reflecting the durability of the underlying GPRS architecture even as it has been extended by EPS, 5G and beyond.

Purpose & Motivation

The destination user term exists because GPRS needed a vocabulary that could describe packet-switched communications without borrowing the circuit-switched notion of a called party. In a circuit-switched call, the called party is a subscriber identified by a telephone number, and the network establishes a dedicated path to that number. In GPRS, the communication is a packet flow towards an address in an external data network, and the recipient may be a host, a server or a mobile station. A new term was required to describe this addressed endpoint in a technology-neutral way.

Defining the destination user in TS 21.905, the overarching 3GPP vocabulary, gives the term a scope wider than GPRS itself. It allows other specifications to refer to the addressed party of a packet communication without redefining it, and it supports the consistent description of services that span multiple access technologies. The companion definition in TS 22.060, the GPRS stage 1 service description, anchors the term in the service requirements from which the GPRS architecture was derived.

The term also addressed a practical problem in early GPRS standardisation: the need to distinguish the bearer from the service. GPRS provides a bearer to a destination user, but the service that uses that bearer — messaging, web access, file transfer, telemetry — is defined elsewhere. By naming the destination user as the entity to which GPRS calls are directed, the specifications make clear that GPRS itself is not concerned with the nature of the communication, only with delivering it to the addressed endpoint. This layering principle has proved durable and is reflected in the way later generations separate the data bearer from the applications that use it.