Forward the text messages to SPAM (7726) and request your carrier block the number.
Forwarding to SPAM alerts your carrier that the number is a spammer, they will investigate and take messages to stop the spam.
http://www.fcc.gov/guides/spam-unwanted-text-messages-and-email
If you have smart phones, there are many apps that can help you block unwanted messages and calls.
Check your phone's app store.
This number sent me this text, and it reads:
FRM:665151763776730
SUBJ:Hey! Was thinking about being a bit of a
MSG:txt me back if u want to see, oh and here is my number 2135878773
Very stupid