You may not have ever heard of TextMarks, but if you've ever sent a text message to 41411, you've used their service. TextMarks is one of several services that makes it easy to provide information by text message. They take away the complexity of registering an SMS shortcode and directly interfacing with cellular providers, and replace it with an API that makes it easy for developers to build SMS-driven services.

TextMarks, and services like it, are commonly used in the transit industry to provide real-time information by text message—send 'nextmuni 15650' to 41411 for an example. But what you may not realize is that such services are actually quite expensive. Steve Munro reported the following from the Toronto Transit Commission's 2012 budget:

Text messaging (sending “next vehicle” info) is expected to cost $1.3m in 2012. The TTC is considering a business model for provision of customer information and expects to make a “pricing decision” in the next few months. I cannot help noting that there are other ways to deliver this information than using SMS, and any review should include web access such as is available from NextBus or from various third-party applications.

Mr. Munro makes an excellent point on the value of making data available over the Web, where it can be disseminated in a far more cost-effective way, and making it available to app developers, who often build their own infrastructure for delivering the data and thus shoulder some of the burden.

But for some transit riders, text messages are still the best way to get transit information. Not everyone has a smartphone; not everyone wants to click through a complicated app. It's easy to text a stop number to an SMS shortcode and get back the desired information. Rather than charging riders for transit information by SMS (as the TTC had intended to do), it may be useful to look at cheaper ways to provide that information that still work for riders without smartphones.
Though may seem counterintuitive, one answer might be Twitter. It seems like the majority of Twitter users access Twitter over the Web, from a desktop PC, or use an app for their smartphone or tablet—so it's natural to wonder how Twitter can help people access information by text message. But Twitter also offers a free SMS interface that supports many mobile carriers around the world. Text messaging users can use Twitter to subscribe to a transit agency's Twitter account on their phone to receive updates by text message. But what about requesting specific information, like when the next bus is coming? For that, you can use Twitter direct messages: send a DM with your stop code, and get a DM back with the information. If you're using Twitter via SMS, you'll get the reply in a text message.

This is precisely the approach that has been taken by the Washington State Department of Transportation. They've set up a number of services which are accessible via Twitter direct message. You can send a DM from the Twitter web site, any Twitter client, or a text message to 40404 (or the applicable shortcode in your country) and get the information—travel times, weather conditions, and more—back in a reply DM. A message like "d wsdot tt bellevue to issaquah", for example, will get information on travel times, based on WSDOT's live traffic data. The same approach could be extended to provide transit information from area transit authorities.

The service take a little more effort to use than one provided through a gateway like TextMarks (you have to follow @wsdot first, either on the Web or by SMS), but once you've done that, you can use it from anywhere you can access Twitter—over the Web, with a smartphone app, or on any mobile phone, by using Twitter's SMS service. What's really interesting about this approach, though, is that in contrast to commercial SMS gateways, Twitter accounts are free to register and use, and there's no extra charge for use of Twitter's SMS service.

Of course, Twitter has to recover their costs somehow, and there's no guarantee that they won't eventually start charging for commercial use of Twitter, or for use of the SMS service, but for now, WSDOT's work represents an innovative and low-cost approach to providing information by text message.