SMS: Short Message Service


Short Message Service, or SMS, is a text-based service for exchanging one- and two-way text messages. If you have ever received a message notifying you that you have a voice mail message on your mobile phone, then you have seen text messaging in action. One-way SMS messages have been available for years and were initially used to provide messages to telephone subscribers alerting them to the fact that they had received a voice mail. Later, news alerts, sports scores, and traffic messages were provided to mobile users as well. Two-way SMS messaging allows messages to be sent to the mobile phone as well as from the mobile phone to other mobile phones, e-mail addresses, or to servers that manage services such as games. Messages sent to the mobile phone are commonly referred to as "mobile terminated," while messages sent from the phone are referred to as "mobile originated." With the advent of two-way messaging, a whole new host of functionality became available. Mobile phone users could use text messaging in an interactive fashion, interacting with others or with servers capable of responding to SMS requests.

Another factor in making SMS messaging more prevalent was inter-carrier messaging. Initially, two-way SMS messaging allowed messages to be sent to or from mobile phones from within the same carrier or to an e-mail address or server capable of responding to SMS requests. Inter-carrier messaging allowed messages originated from a mobile phone on one carrier's network to be sent to a mobile phone on another carrier's network. This was a watershed event, as it prompted tremendous growth in SMS traffic.

SMS Technology

SMS Messages are exchanged with consumers via the carrier's Short Message Service Center (SMSC). The SMSC is the bridge between the TCP/IP and the wireless Signaling System Seven (SS7) protocols. In an ideal world, SMS applications would be able to directly interface with the SMSC so that the application can be technically "as close to the consumer" as possible. Direct SMSC access enables the developer to guarantee message delivery, send enhanced binary content such as bitmaps and ring tones, and receive mobile-originated messages in a timely fashion.

Unfortunately, the carrier's SMSC is typically not available for direct access by application developers. Some carriers will provide direct access to third-party SMS delivery agents that in turn will resell access to other application providers. This is a valid "second choice" for developers if direct SMSC access is not possible.

Most carriers also provide publicly accessible Internet gateways that relay Web (HTTP) and e-mail (SMTP) messages to the SMSC. Some carriers also provide mobile-originated e-mail gateways that enable subscribers to send Internet e-mail via SMS. These gateways can serve as a "last resort" for SMS application developers that require one- and two-way SMS access to the carrier. This is the least-preferred technique, as it is difficult to guarantee SMS message delivery, delivery is not always immediate, and there is no support for direct billing to the consumer.

Figure 2.6.2 illustrates the various SMS connectivity options. The carrier's SMSC is typically available only to select third parties. The carrier's Internet gateway provides public access to basic SMS capabilities. The aggregator can offer connectivity and billing services.

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Figure 2.6.2: SMS connectivity options.




Secrets of the Game Business
Secrets of the Game Business (Game Development Series)
ISBN: 1584502827
EAN: 2147483647
Year: 2005
Pages: 275

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