I am sure AT&T is doing everything in its power to reduce the amount of spam that hits my text plan , even though they earn money from each spam . They're just that kind of company.
As best I can tell there are three sources for the AT&T carried text spam I get. One source has an 8 digit number; I forward those to AT&T's spam service and, annoyingly, have to send a second text with the number retyped. I have no idea if this does anything, or if it even reverses AT&T's charge.
The second source has a "short code". AT&T says I'm to to reply "STOP" to these. I assume these are AT&T "approved" and are never classified as spam, even when they sell criminal scams.
The third source is via an email gateway to my "device default email address" of "email@example.com":
[To] Block all email messages sent to your device's default email address (i.e., firstname.lastname@example.org). Create an email alias for your phone in Messaging Preferences, then change the Mobile Number Control settings so that only those text messages addressed to your email alias will be delivered to your wireless device.
I had no idea that it was possible to send email to my SMS service -- we were never part of the SMS era. What a perfect scam setup.
Sounds like the "fix" is to create an SMS email address that is then kept secret. This isn't done through AT&T's usual mobile site, it's a separate service with its own password (max 8 character?!) and registration process: http://mymessages.wireless.att.com
I'll look at doing this for our phones.
 Thanks to iMessage, and H2O Wireless and old AT&T-locked iPhones for the kids, our family does very little SMS. So it's cheaper to pay 20 cents/text than to sign up for AT&T's desperately overpriced text plans.
 Obviously I'm joking. If AT&T were serious about blocking spam they'd let us block all short code text.
Update: I recommend this reference: http://www.howtogeek.com/howto/41123/how-do-you-block-annoying-text-message-sms-spam/. As I half-suspected, the STOP approach is not the best. I'm surprised to learn that as bad as AT&T is, everyone else is worse. Blocking email gateways also blocks many notification services (airlines, Google Calendar, etc) -- but I can live without those. Also Android phones have some pretty good SMS blocking methods, iPhones have none.
Update 2: Weird coincidence -- or not. NYT article on the topic today. They mention Cloudmark's emerging "7227" service, but nothing about providing options to block all short codes, or all email gateway spam, and nothing about the revenue carriers make from text spam. Sigh.
Update 4/9/12: I blocked all email text or multimedia messages and all MOBILENUMBER@txt.att.net and MOBILENUMBER@mms.att.net messages. There are also block and allow lists I might play with later, but for now I blocked everything. I didn't set up an alias.
Unfortunately (cough) AT&T doesn't implement similar blocking for SMS:
Text messages sent via email can also be blocked directly from your handset. When you receive an email that you wish to block, simply reply to the email with the word "block" in the body of your message. The sender's email address will be added to your Block List. Note: this does not apply for mobile-to-mobile text messages.
I suspect these blocks won't make much difference, but I'll see.
... they use customized computer programs to generate and send hundreds of messages in a matter of minutes, varying the wording, capitalization, and punctuation to evade the phone companies' rudimentary spam filters. And thanks to a fiendish device called a SIM box, the spammers can plug dozens, even hundreds, of SIM cards—each representing a different mobile phone number—into a single phone. By the time you’ve received a text and reported the number, there's a good chance it has been used hundreds of times and discarded...
... Blocking messages from the Internet is also unlikely to cut down on the volume of spam you receive. Sending texts from the Web used to be a popular method for mobile spammers, who could try endless random combinations of numbers in hopes of a few hits. But unlimited texting plans made that approach less attractive to spammers, who know that such messages can easily be blocked. Though it’s still worth doing, don’t expect a magic bullet...
... a third of all text messages in China today are spam...
... They knew unlimited texting plans were in the pipeline. They should’ve known that unlimited plans mean seemingly unlimited spam...
I think my son has been responding to some of these spams, that may explain the 200 texts he's received. The only solution seems to be to turn off SMS service altogether. Interesting observation that the spam deluge is a result of unlimited texting plans (free spam), and that China saw it first.