Starting August 21, your choice of AT&T SMS plans are either 20 cents for every text message sent or received, or $20 per month for individuals and $30 per month for families of up to five lines.

If you're not a callous-thumbed teen sending between and text messages every month, the English language , and want to keep your existing 1000 texts plan, AT&T will grandfather you in at the same $10 per month rate. It's a benevolent gesture rare among carriers, although AT&T did it previously with its now-extinct .

But that fee-per-text plan is considerably less than benevolent, and it's not limited to AT&T. If a text message is limited to 160 bytes, and each text costs 20 cents, that means AT&T has an SMS data transfer charge of . Conclusion? Be thankful for unlimited texting plans -- just what AT&T intends.