Although, this might be old stuffs for many of the At&t users, we are posting for those millions of iPhone newbies. To block unwanted Sms or to set up alias sms account, go to http://mymessages.wireless.att.com/ and register there. This is a free service provided by At&t. During registration process you are required to enter registration code which you get via sms. After registration, log in and started blocking or customizing sms in your phone.
You can block all email which come as sms or block multimedia . You can also create block and allow list. For blocking the email which come as sms from your cellphone simply type “block” in the body and reply it to the sender.
Under message option, you can set up message preferences and set up ur alias account to get sms. You can also control the length of the sms under “Block Incoming” option. This allows you to set the number of segments that are delivered to your phone when messages are longer than 160 characters.