IP Service

Description

An IP service, as defined in 3GPP TS 22.258 and TS 22.978, is a service that utilizes an IP bearer provided by an IP service provider. The fundamental characteristic of an IP service is that data traffic is routed based on the IP addresses of the sender and receiver(s), leveraging the inherent addressing and routing capabilities of the Internet Protocol. This definition distinguishes IP services from other types of services that might use different addressing or routing mechanisms, such as those based on telephone numbers or other identifiers.

The concept of an IP service is broad and encompasses a wide range of applications and communication types. Examples include web browsing, email, file transfer, voice over IP (VoIP), video streaming, online gaming, and machine-to-machine (M2M) communications. In the context of 3GPP networks, IP services are typically delivered over mobile broadband connections, where the user equipment (UE) obtains an IP address and can communicate with other IP endpoints. The IP bearer provided by the network ensures connectivity between the UE and the external packet data network (PDN) or between UEs.

The IP service provider is the entity that offers the IP service to users. This provider may be a mobile network operator (MNO) or a third-party service provider. The MNO provides the IP bearer (connectivity) and may also offer its own IP services, such as IMS-based telephony. Third-party providers, such as Internet service providers or application providers, offer services that run over the MNO's IP bearer. The definition explicitly notes that an operator of an IMS would be considered an IP service provider, highlighting that IMS services are a subset of IP services.

From an architectural perspective, IP services rely on the packet-switched domain of the mobile network. In 2G/3G, this is the GPRS/UMTS packet core; in LTE, the Evolved Packet Core (EPC); and in 5G, the 5G Core (5GC). The network establishes a bearer (e.g., EPS bearer, PDU session) that provides IP connectivity with specific QoS characteristics. The IP service then uses this bearer to exchange IP packets. The routing of these packets is based on IP addresses, which may be dynamically assigned or statically configured. Network address translation (NAT) may be used in some cases, but the fundamental principle remains IP address-based routing.

IP services are central to the modern mobile ecosystem. They enable the vast array of over-the-top (OTT) applications and services that users access on their smartphones and other devices. The 3GPP specifications for IP services, such as TS 22.258 (Service requirements for the All-IP Network) and TS 22.978 (All-IP Network (AIPN) feasibility study), define requirements for supporting IP services efficiently, including aspects like IP address management, QoS, mobility, and security. These specifications were part of the evolution towards an all-IP network, where all services, including voice, are delivered over IP.

Purpose & Motivation

The IP service concept was formalized to provide a clear definition for services that operate over IP-based mobile networks. As mobile networks evolved from circuit-switched to packet-switched, and eventually to all-IP architectures, it became necessary to distinguish services that rely on IP addressing and routing from those that use other paradigms. The definition helps in specifying requirements for network capabilities, such as IP address allocation, QoS, and mobility management, to support a wide range of IP-based applications.

Historically, mobile networks were primarily designed for voice telephony, with data services as an afterthought. The introduction of GPRS in 2G and later UMTS in 3G enabled packet-switched data, but these were often limited in bandwidth and QoS. The concept of an IP service gained prominence with the vision of an All-IP Network (AIPN), which aimed to provide a unified IP-based infrastructure for all services. 3GPP TS 22.258 and TS 22.978 were developed to study and specify the requirements for such a network, including the support for IP services with varying QoS and mobility needs.

The IP service definition solves the problem of ambiguity in describing services that use IP. By explicitly stating that routing is based on IP addresses, it clarifies that the service is not tied to specific access technologies or lower-layer identifiers. This abstraction allows operators and service providers to design and deploy services that can work across different access networks (e.g., Wi-Fi, LTE, 5G) as long as IP connectivity is available. It also facilitates the development of policy and charging rules that can be applied based on IP flows, which is essential for managing network resources and monetizing services.