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The long and short of SMS

Text messaging, the wireless way

By Joanie Wexler
Net.Worker, 08/10/01

Perhaps one of the least hyped but most useful wireless technologies in operation today is Short Message Service. SMS is one of the few wireless messaging standards to have gained widespread acceptance. Support for SMS is generally bundled into digital (2G) GSM, Code Division Multiple Access (CDMA) and Time Division Multiple Access (TDMA) phones - as well as proprietary mobile radio network handsets and even some analog phones - for enabling inexpensive wireless text messaging.

Depending on your point of view, the strength of SMS and its Achilles' heel might both be the same thing. By definition, SMS enables limited-size messages. This is because in digital systems, the SMS messages run in the same control channel as the call setup data. You could view the restriction on message length as a hindrance or a blessing. If you are the wordy sort, you might be frustrated by the length limits. But for the delivery of notifications and alerts, SMS provides a low-cost communications mechanism that can take place at the same time users are talking on their digital cellular phones.

GSM and narrowband TDMA support message lengths of 160 characters. GSM supports two-way messaging, while TDMA enables messages to be received from the network only. CDMA supports messages of 256 bytes and two-way messaging.

Note, though, that SMS interoperability across different carrier networks in North America has been problematic. SMS messages often cannot be sent from one type of network technology to another or one carrier (say, from a GSM network to a CDMA network). This has not been a problem in Europe, where GSM is used ubiquitously. But in North America and other regions where multiple digital cellular technologies are at play, usage has been stunted. The good news is that within the past few months, at least two companies - CMG Wireless Data Solutions and InfoSpace - have said they are building internetwork gateways to enable cross-network SMS communications. MobileSys, whose global wireless network connects to many of the world's large wireless networks using gateways, says that it can pass SMS messages among networks regardless of the airlink protocol.

SMS applications
Some interesting SMS applications can be found in the banking sector, among retail businesses such as restaurants and in the transportation industry, which uses SMS for location tracking.

In general, automated teller machine transactions are less costly to a financial organization than those involving live tellers, and Internet transactions are less expensive still. SMS, often in conjunction with Wireless Application Protocol, can be used to enable wireless customers to check balances, transfer funds between accounts and so forth using their cell phones - enhancing customer service while helping control costs.

In a restaurant scenario, if a waitperson can complete a credit card transaction right at the customer's table using SMS, that removes another necessary roundtrip (to a point-of-sale terminal and back again to the patron's table). Anyone who has ever been dying to leave a restaurant while their waitperson disappears for what seems to be eons can likely see the value in this from the customer side. Meanwhile, from the business' point of view, the waitperson becomes more productive.

Tracking the location of a truck or the goods a truck is carrying has long proven to be a critically competitive component to the transportation business. Location tracking can be a good candidate for an SMS application because only small amounts of data, such as latitude, longitude and time of day, must be transmitted.

Wexler is an independent networking technology writer/editor in Campbell, Calif. She can be reached at joanie@jwexler.com.