Marketers using text messaging beware. A recent federal court ruling says sending ads in text messages potentially violates the law.

In a nutshell, here's the situation:

• The Ninth Circuit Court of Appeals said a lower court mistakenly absolved Simon & Shuster and its agency partner ipsh! of violating telecommunications law in sending text messages to promote Stephen King's novel "The Cell" in 2006.
• The case hinges on two critical questions: Was an auto-dialing system used for the campaign? And, should a text message be defined as a "call"?

The case, which now goes back to the lower court for review, has galvanized mobile vendors like Shane Neman, CEO of Ez Texting, whose own company faces a similar suit. Neman has organized the Mobile Advocacy Coalition, which intends to ask the FCC to recognize vendors as "mere conduits" of text messaging, giving them an exemption from this kind of legal action - an exemption the carriers already enjoy, he notes. The coalition is not seeking to exempt unscrupulous marketers who violate the law by sending unsolicited text messages.

This is a very important case for marketers because it could result in new restrictions on the use of text messaging. It also points to the growing pains for mobile as it becomes a more established marketing platform.