Multimedia Messaging Relay/Server

Description

The Multimedia Messaging Relay/Server (MMSR/S) is a network functional entity defined in early 3GPP releases that combines the capabilities of a Multimedia Messaging Service Relay (MMS Relay) and a Multimedia Messaging Service Server (MMS Server). In the MMS architecture, these functions are often conceptualized separately: the MMS Relay handles protocol conversion and message transfer between different networks (e.g., between a mobile network and the Internet), while the MMS Server provides storage and handling logic, such as managing user profiles and message waiting indications. The MMSR/S represents an integrated implementation of these two logical functions within a single physical or logical network node.

Operationally, the MMSR/S acts as the central hub for MMS traffic. When a user sends an MMS, the MMS User Agent (MMS UA) submits the message to the MMSR/S. The MMSR/S then stores the message, identifies the recipient, and determines the best route for delivery. If the recipient is on the same network, it may forward the message directly. If the recipient is on a different network (e.g., another mobile operator or an email server), the MMSR/S performs the necessary interworking and protocol adaptations. It uses standards like MM1 (between UA and MMSE), MM3 (to external servers), and MM4 (to other MMSEs). The server component manages features like message expiry, charging data generation, and delivery reporting.

Key internal components include the message store, the interworking function (IWF), the routing engine, and the charging gateway interface. The MMSR/S must support high availability and scalability to handle large volumes of multimedia content. Its integrated design simplified early MMS deployments by reducing the number of discrete network elements required, though later architectures often separated these functions for greater flexibility and scalability.

Purpose & Motivation

The MMSR/S was specified to provide a concrete, implementable network element for early deployments of Multimedia Messaging Service (MMS). As MMS evolved from concept to commercial service, network operators needed a clear blueprint for the core infrastructure. Defining a combined Relay/Server entity offered a practical solution that encapsulated the essential store-and-forward and gateway functions in one system. This reduced implementation complexity and accelerated time-to-market for the first MMS offerings.

It addressed the need for a central node that could interface with both the mobile packet core (e.g., via GGSN) and external messaging systems like email or legacy SMS centers. The integrated MMSR/S handled the critical problem of interoperability—translating between the WAP or HTTP-based protocols used in the mobile domain and the SMTP or other protocols used externally. By combining relay and server functions, it ensured consistent message handling, charging, and subscriber management from a single point of control. This model was particularly suited for the initial phase of MMS where service scale and feature sets were more limited.

Key Features

• Combines the message routing/interworking functions of an MMS Relay with the storage and service logic of an MMS Server
• Provides store-and-forward functionality for multimedia messages, ensuring delivery even if the recipient is offline
• Performs protocol conversion and adaptation for interworking with external messaging systems (e.g., email, other MMS providers)
• Generates charging data records (CDRs) for billing purposes based on 3GPP specifications
• Manages message expiration, delivery reports, and read-reply reports
• Supports standardized interfaces (MM1, MM3, MM4) for communication with user agents and other network elements

Evolution Across Releases

Defining Specifications