For text messages: forwarding any text message spam you get to the short code  “7726,” which spells “spam” on most phones, to alert your network operator to the abuse. ATT won't accept 7726 But they will accept BLOCK and return a message that the web site is blocked. forward the texts to 7726 or BLOCK, depending on your phone carrier.
http://www.att.com/esupport/article.jsp?sid=KB115812

Just got a text from this number saying it's a link from someone that I know. I haven't spoken or seen this person in like 7 years. polo4u.us/.......i think it's time to change my number

Got a message from this number. Takes you to a Marco Polo app to install. Have not talked to this person in over 3 years and have no reason to