Spammer.
You can forward the number to your cell phone carrier.
ATT example:
http://www.att.com/esupport/article.jsp?sid=KB115812&cv=820&title=Block%20spam%20text%20messages%20on%20your%20wireless%20phone#fbid=8UEKI1NenTx
Scammers and Spammers of Craigslist
Spammer.
You can forward the number to your cell phone carrier.
ATT example:
http://www.att.com/esupport/article.jsp?sid=KB115812&cv=820&title=Block%20spam%20text%20messages%20on%20your%20wireless%20phone#fbid=8UEKI1NenTx