14.4 Presence and Messaging

With approximately 667 million text messages sent across the globe every day, mobile operators have been reaping easy money from SMS (short message service). Today's largely person-to-person messaging market will be one of the main drivers toward increased mobile data adoption, crucial to the future of 3G services. Currently cellular operators in mature markets obtain 5 to 20% of their total revenues from SMS. Experts in the sector forecast that globally messaging revenues will constitute 11% of total cellular revenues by 2006, up from a global average of 2.7% in 2000. The value of the current global SMS market, worth U.S.$13 billion in 2001, will more than quadruple by 2006 to over U.S.$69 billion. Western Europe will be the world's leading market, with total mobile messaging revenues of U.S.$30 billion by the end of 2006, followed by the Asia Pacific region, generating U.S.$22 billion in mobile messaging revenues.

In this framework, the convergence of multimedia applications and the mobile phone is on its way. New applications to replace today's "not-so-successful" WAP interfaces are in the works. Besides SMS, which appeals in large part to young people, new "serious" applications will be enabled with the "always on" 2.5 and 3G mobile network technologies, which will greatly increase the flexibility and usefulness of applications such as mobile banking, entertainment services, and multimedia messaging applications in general.

In this section we provide a description of multimedia messaging applications, focusing on the background of their success and evolution, and describing what will characterize these applications and what types of services are to be expected.

14.4.1 Evolution of Messaging

The Short Message Service (SMS) is a technology that was introduced in the early 1990s when the Internet was still unknown to the general public. SMS can be seen as the starting point of convergence between the Internet and the mobile world. In fact, long before the appearance of the Wireless Application Protocol (WAP) and other ways to access the Internet, wireless users were receiving simple information such as stock quotes, weather, train schedules, flight information, and access to e-mail using SMS. The widespread use of SMS is mainly due to the ability of young people to master the user interface and their desire to communicate cheaply with their friends even in situations where a phone call would not be possible. The popularity of SMS has definitely triggered the general interest in mobile data solutions and has shown to the industry the advantages of "always on" services, setting the stage for more evolved services.

The introduction of the SIM application toolkit standard opened a set of new opportunities: service providers can change or download applications in the wireless device over the air, and the user can be offered a menu-based choice of services, as well as support for new services and advanced security features such as those required for banking applications. However, at first only GSM subscribers could benefit from it and suffered all the inherent limitations of the SMS bearer: for example, limited bandwidth available and short message length.

The effort to overcome these constraints and allow wireless users easier access to Internet content regardless of the wireless technology led to the creation of the WAP standard. However, its popularity is still low, and WAP's true potential will be exploited when 2.5G and 3G packet switched services are introduced on a large scale.

In the meantime, while WAP was being developed, SMS evolved. Proprietary protocols have appeared, such as Nokia's "Smart Messaging," and then standards were formed , such as Enhanced Message Services (EMS). EMS allows simultaneous downloading of ring tones, icons, and text, exploiting the current SMS network infrastructure.

The Mobile Station Application Environment (MMxE) standard, currently being defined by 3GPP, will speed up the convergence between the Internet and the wireless world. MMxE aims at creating a standard environment for wireless applications by defining a Java environment on the phone and incorporates SIM card technology. In addition, MMxE supports standard Internet protocols for transport, security, and applications. Thanks to MMxE, in this environment, the wireless user has new possibilities that are currently available only to laptop and desktop computer users (e.g., download client applications such as interactive games , execute services on remote servers, and interact with another MMxE user in a variety of scenarios). MMxE is a powerful enabling technology for the multimedia message service (MMS) that will support messages combining text, images, sounds, and video clips in a variety of formats. MMS will be the first mobile service to utilize open Internet standards for messaging, such as multipurpose Internet mail extensions (MIME), Simple Mail Transfer Protocol (SMTP), and Hypertext Transfer Protocol (HTTP).

The technology for advanced service and open access to the Internet already exists. Mobile phones can provide streaming video, play music, deliver news and other content, facilitate financial transactions, and provide entertainment, among many other things. However, we need to keep in mind the difference between what these devices can provide and what users actually want. The greater majority of the consumers are not technically skilled to understand the full potential of these new technologies. In order for the new services and technologies to be successful and trigger even more evolution, it is essential to educate users, make them aware of what they can do, and develop services that keep them interested and coming back for more. For this reason, the focus in the wireless community has been on fun, youth, and communities, with an offer of services that are entertaining, interactive, and easy to use. To maintain the success, services must evolve and continually provoke the users' interests and never leave them unsatisfied or bored. Today's youth is the most important part of the market for the evolution of wireless services, since they will drive the convergence revolution, in the same way that they drove the popularity of the early SMS. They grew up with technology, they have seen their world through screens and windows , and they are the early adopters that set new trends. In the future, guys and girls might flirt and date through video calls on their cellular phones. It is easy to foresee that the more these services aggregate people into a wireless community, the more successful they will be.

Although mobile phones have already partially changed the way we interact with others, we can easily foresee that thanks to new capabilities and applications, mobile phones will change the way we live, exchange information, have fun, and interact with other human beings.

Examples of the trend toward mobile messaging and mobile multimedia are the initiative of companies like Nokia and Lycos Europe to work together to develop multimedia messaging services. Lycos Europe recently launched its Mobile Channel, merging its communities with the power of mobile technology. The new channel is currently built around SMS service, and extending Lycos Mobile with new MMS features and MMS content gives the users ”in a community environment ”an even more exciting experience of informative and entertaining MMS services. Features such as composing multimedia messages out of ready-made Lycos content or personally created images will make MMS more accessible to the consumer.

14.4.2 Toward Multimedia Messaging

MMS is a natural continuation of short message service (SMS) and has capability similar to e-mail. Through MMS, text, photo images, voice, and video clips can be sent from one mobile device to another. Messages are sent to either an MSISDN address (i.e., mobile phone number) or an e-mail address, and MMS messages can be sent to multiple recipients. The receiver is notified of the incoming message with an MMS notification using SMS and needs to retrieve the message from the network.

MMS is a highly appealing service for practical use as well as sharing and having fun. Possible usage situations for the MMS could be sending a love song, a substitute for postcards, or on-the-job usage, for instance, at construction sites, during real-estate dealings, or even with insurance investigations.

MMS is considered the most versatile standardized messaging service to date, including all the features and content types of preceding messaging services. Multimedia messaging service is an open standard supported by 3GPP and WAP Forum and is bearer independent. Figure 14-2 shows the architecture of the MMS defined by 3GPP.

Figure 14-2. Architectural elements of 3GPP MMS.

The WAP forum has standardized the MMS architecture. The main components are as follows :

MMS Client is the application in the user's terminal. The client will utilize the general WAP client services like WIM identity. Image and multimedia content rendering is an MMS-specific function.

MMS Relay is the point that the client connects to. The proxy may be integrated with the MMS server.

MMS Server stores the multimedia messages.

Email Server is the traditional Internet mail service with the SMTP, IMAP, and/or POP interfaces.

Legacy Wireless Messaging systems exist already in the 2G cellular networks. Text messaging with the 2G subscribers will be needed until MMS gains large enough user base.

In the MMS model, an active client can pull messages from the proxy when convenient . The proxy can also push content to the client if such service has been subscribed to. In the low-bandwidth cellular access case, a WAP gateway optimizes the transport between the client and the proxy. The MMS proxy relay forwards client-originated e-mail in the MIME format to the e-mail server with the SMTP protocol. In the downlink direction, the proxy converts MIME to the MMS format. An X-Mms- prefix in the MIME header name indicates MMS-specific header field. MMS systems handle all the header fields while non-MMS systems ignore the prefixed ones. The proxy retrieves e-mail with the POP and/or IMAP protocol. The MMS interface between two proxies uses the normal SMTP and its service extensions (ESMTP) for the interconnection. ESMTP is specified in RFC 1869 and RFC 1870.

Both Internet and wireless network addressing are possible with MMS, with User@realm address being the familiar e-mail format, whereas wireless network addressing traditionally used PSTN phone numbers to identify a device, with IP addresses as a later addition.

Advanced multimedia messages may contain a significant amount of additional information to present the content in the receiver's terminal. In the browsing context, HTML layout and form commands are the most familiar examples, but voice and video stream synchronization with other simultaneous media requires even more advanced mechanisms. Presentation and rendering capabilities in the receiving terminals vary: Low-end terminals may ignore some of the synchronization and timing information. However, the specification does enable more advanced devices with a large display and high-quality loudspeakers. MMS specification uses Wireless Markup Language (WML) for hypertext sequencing and layout. Synchronized Multimedia Integration Language (SMIL) (based on XML) provides multimedia timing and animation capabilities.

MMS messages carry the content and the presentation language, the latter containing pointers to the multimedia objects in the message. MMS security builds on the underlying WAP and Internet protocols and adopts wireless transport layer security (WTLS) to protect data confidentiality and integrity; a Wireless Application Protocol identity module (WIM) to store sensitive key material and participate in the authentication protocol when setting up a security association; WAP public key infrastructure (PKI) definition to indicate how the Internet PKI standards should be used in the wireless messaging, with the WIM storing the user and device certificates; S/MIME to protect MIME confidentiality and integrity when carried over SMTP; and finally, IPsec to protect the transmission between the servers when application-level security (S/MIME) is not suitable.

14.4.3 Multimedia Messaging Technologies

There are several different technologies for multimedia content transmission, and it is not yet clear which of the technologies best suits which markets. The multimedia messaging technologies currently available are as follows:

• Enhanced messaging service : EMS extends the popularity and profitability of SMS by letting subscribers add images, animations, sounds, and style.

• Smart messaging: This is a Nokia proprietary system for delivering various kinds of messages from service providers to mobile phone users and between mobile phone users. The most common and popular services so far are the delivery of ringing tones and operator logos.

• E-mail

• Multimedia messaging service

• Mobile IM (Instant Messaging): It is similar to fixed-line services available from providers such as AOL, ICQ, MSN, and Yahoo, and enables subscribers to see via the presence service capability which of their contacts is currently using the service so that they can enter into an exchange of messages.

In the following section some examples of the services that will be available in future multimedia messaging systems are described:

• Interactive multimedia information retrieval: This is a device-independent Internet portal that allows to request content with any device and to push immediately generated answers to any user-specified destination.

• Mobile E-mail: Makes email accessible from any mobile phone by liberating e-mail access from its dependence on the PC. This enables users to send, receive, and process e-mail messages and personal information no matter where they are.

• Push proxy gateway: Enables mobile operators to push information and content (from simple texts to pictures and video clips) to mobile subscribers, without a previous user request and to any mobile device in 2G, 2.5G, and 3G networks.

• Video messaging: Allows subscribers to compose video messages using a Web interface on a PC or mobile device.

• Voicemail information services: Provides subscribers with easy access to precisely the information they want, when they want it. The service allows operators to deploy information services to offer subscribers 24- hour connectivity to a wide range of information available through the Internet.

14.4.4 Presence Service

The IETF community has recently developed two IP services that are being adopted in wireless networks and have the opportunity to revolutionize mobile services. Instant Messaging and Presence (IM/P) services provide a way to exchange content and user status information inside a user group .

The idea behind these services is that, before the message exchange between nodes, the communicating parties must register their presence information to the presence server. Users can indicate to the presence server their status and "mood" (i.e., whether the user is available to receive incoming communications from all users or only for some user defined groups). At the same time, the user can select whether her presence can be made public or if only a restricted set of other parties can be aware of the user presence. Personal status and "mood" information will tell the possible callers if it is a proper moment to set up a session. Parties interested in the presence information of a given user can request such information when needed or can subscribe with the presence server to be immediately informed of changes in the presence information of the user so that they know immediately when the other party becomes available. Attributes such as location of the user can also be added to the presence service and this would enhance the usefulness of presence service.

SIP (Session Initiation Protocol) is used to support these services. SIP signaling controls the sessions and may contain user payload such as a brief text message or caller's personal information. However, the bulk of the payload should be carried over the normal e-mail, voice call, and Web browsing protocols (i.e., SMTP, RTP, and HTTP). SIP message primitive provides communication via a proxy server or directly between the endpoints in a peer-to-peer fashion. An advanced authentication and authorization mechanism is used to manage the user groups and the visibility of the data, as the presence information is highly private in nature.

Instant Messages and Presence service will become one of the most common services in future networks. 3GPP and 3GGP2 have considered this and included the services as part of their service provisioning mechanisms.