A vastly underused component of communications applications, especially as it relates to business communications, is SMS or text messages. Text messages have many unique practical advantages that become valuable in the real world of the mobile workforce. First, and perhaps foremost, text messages work nearly everywhere. When signals are too low for a voice call, text messages are your best bet, even better than e-mails which require a stable data connection. Text messages are a store and forward technology, so workers can read them when they are available. Text messages can be read without disturbing those around you. Text messages are the best technology for communicating detailed, but short, information such as part numbers or other phone numbers, because the recipient is not required to grab a pen to write it down on a piece of paper, which might get lost. The number is safe on the phone, and very hard to lose. The downsides are few - 168 characters per message - but surmountable.
There's a large number of providers today that you can sign up for to send text messages. I use Strike Iron's Global SMS Pro, because it's reliable, easy to setup and and simple to pay for. Sending text messages, however, is a much easier task than receiving them. Since text messages use the PSTN's SS7 network, it's a pain not only because of the equipment requirements, but the regulatory requirements. Signing up to receive text messages is a commitment and an investment, and typically costs over a thousand dollars to register your inbound number (called the short code) and a over a thousand dollars a month to maintain it, and that's before you start paying for traffic. Sending is typically much cheaper, since you only pay your ten cents or so a message to your provider.
This is where 411Sync's service comes in. 411Sync provides the developer with a free, and fairly easy, way of accepting inbound text messages. The 411Sync service provides a freely customizable way of enabling mobile search, but you can extend it to whatever your needs are. When you send a text message to the service, you specify a keyword (such as 'red_sox_score') and whatever parameters you desire (such as 'today'), and it will pass it to a standard Web CGI script that you specify when you create the keyword. Your program takes the parameter, calculates an answer, and passes it back as a formatted RSS or Atom message. 411Sync passes that answer back to the phone, with an ad attached. In our Red Sox example, if you sent a text message to 411Sync of red_sox_score today, it would respond with something like Red Sox 10, Yankees 0. You would register a program with red_sox_score, and it would be called with the parameter "today".
The business example? How about mobile workforce automation, with the target audience being a service technician. After you finish a job, you could send a message to your service like "wrico tom 5083649972 complete". Tom would be the technician's name, and the number would be the contact number of the job, and the keyword would tell the front office that the job is complete. The CGI script might record the time spent on the job for billing purposes, then as an answer, provide the address of the next job. In fact, for mobile status reporting, 411Sync is the best, and cheapest game in town. Check it out.