411 on SMS. No LOL. OK? * (Keeping in Touch).(Buyers Guide)

Cell phones aren't just for live chats anymore. Short-messaging service-missives of 25 words or less, painstakingly tapped in using the phone's keypad-is all the rage. Verizon Wireless, the nation's largest wireless carrier, says that the number of messages it carried increased more than 700 percent over the course of 2002.

Although driven by teens and young adults who seemingly aren't satisfied with online instant messaging, SMS can be very useful for sending urgent messages to family members or co-workers. A text message occupies a smaller chunk of the cellular transmission spectrum and so may go through when there isn't enough capacity to handle a voice call. Still, even these brief text messages don't always get through.

System glitches sometime "misaddress" messages en route, and equipment can break down. AT&T Wireless, Verizon Wireless, and other cellular carriers rely on smaller service companies to translate text messages sent to other carriers using different digital formats. Those service companies sometimes drop messages. Messages that enter the network but can't be delivered immediately are typically held several days. Undelivered messages are eventually deleted.

Keynote Systems, a San ...