Text messages, those lovely succinct 160 character bursts of the human expression that are infinitely more practical than a phone call, are in danger. According to a report published earlier this week by the analyst firm Chetan Sharma, the average American sent 678 text messages per month during the third quarter. That’s down from 696 text messages in Q2. Why is this seemingly small drop so significant? Because this is the first time that a decline has been recorded.

So why are people texting less? Here’s a few obvious ideas: Since smartphone penetration in the United States has now exceeded 50%, that means the average American carries a device in their pocket that can do email, Twitter, Facebook, WhatsApp, Viber, and various other services. Those services don’t need to use the ancient text message infrastructure to operate. Just look at Apple’s iPhone, which by default uses iMessage to text between other iPhone users. Considering how many people in America have iPhones, this drop was pretty much guaranteed to happen.

What are operators going to do to recoup the revenues lost from the decline of texting? Easy, they’re going to start charging more for data. Most operators have also already made text messaging an unlimited or nothing proposition. You either pay $20 per month and can send as many texts as you want, or you pay absolutely nothing on your monthly phone bill, but then get price gouged to the tune of $0.25 per text. That scare tactic forces people to sign up for the unlimited plan, irrespective of the amount of text messages they know they’ll send in any given billing cycle.

Back to iMessage for a second, we’re really curious as to why Google hasn’t rolled out something similar. Yes, every Android device has Google Talk, but that’s not the same. Services like iMessage, WhatsApp, and Viber are tied to your phone number, not your email address. That’s the key difference.