Chances are your SMS, or text, marketing campaign that you’ve been running may start to see a decline in participation. According to the CTIA, a wireless trade group, more than 1 trillion text messages were sent in the second half of 2010. While 1 trillion may seem like a lot, it’s actually just an 8.7% increase from the previous 6 months, the lowest gain in a decade.

The reason for the small gain? Analysts believe that text messaging may be too expensive for consumers who don’t have an unlimited plan. In addition, major companies are coming out with alternatives to texting that work within their operating systems. For example, the WSJ noted, “Just this week, Apple showed off an application that will allow iPhone and iPad owners to bypass carriers and send text messages over the Internet to other people with Apple devices.”

For marketers, running SMS campaigns can be an attractive means to deliver news, promotions or contests to customers. If the customer is willing to opt-in, then sending a text message can offer high open and conversion rates because of the personal nature of the channel. Usually, consumers only text with their closest friends and family.

With the rate of texts being sent dropping, be sure to keep a close eye on your SMS campaigns and your customers’ participation. Developing your own, branded mobile application for communicating with customers may become an attractive alternative.

If you start to see a decline in conversions, it might be time to ask yourself, “Is the juice worth the squeeze?”