Can text message spam be forever cast into the darkness from whence it came?
Your phone service is probably the one selling your information to the spammers. Their advice to write back the spammers is ridiculous, since that will only cost you more money and it is useless. See if you can opt out of every single marketing gee-gaw you have associated with your phone and every other vendor you deal with. The problem with all marketers is that you are considered automatically opted in unless you specifically ask to opt out. Opt out of everything you can– get off junk mail lists, get on the Federal Do Not Call list, tell your bank, credit card companies to opt you out, notify the DMV you do not want your information sold, opt out at all the credit reporting bureaus. It will mean less junk mail and spam and it will also lessen your visibility to possible identity theft.