Don’t you just hate all the text message spam on your iPhone? Wish you could
block it? Here’s how to get ride of almost all of it.
Most text spam is send to you phone via the email to text feature that wireless
carriers have. The spammers send their junk to MobileNumber@txt.att.net or
MobileNumber@mms.att.net.
By default this "feature" is turned on for all phones. To turn it off you need
to go to the AT&T website and register. Then change your preferences.
What, can't find it on the AT&T website? Don't worry you are not alone. They
make it almost impossible to find.
While most people don't pay per text they receive some do and even if you have a
plan the spam uses up your month allotment. So it's in AT&Ts best interest to
make it as hard for you to avoid text messages as possible.
Here's a link to where you need to go
http://mymessages.wireless.att.com.
Click the "Register now" link.

Fill out the registration form. The box you put your cell number in is 2/3 the
way down the page, not at the top where you would expect it to be. Don't forget
to put in an answer for your security question and check off the "I have
read..." check box.

Click next. They will send a registration number to your phone as a text
message. Enter the registration number into the box on the form and hit submit.

Now you can log in to your account using your phone number and the password you
chose at
http://mymessages.wireless.att.com.

Check off "Block all text messages sent to you as email" and "Block all
multimedia messages sent to you as email".
Hit the submit button at the bottom of the page.

There you go, no more annoying spam.