Stopping SPAM–Some useful advice from the Money Saving Expert

SPAM TEXT – If you receive a text from an organisation you know and the details of the sender are clear text back STOP.  If the text is anonymous DO NOT!  They will add your number to a database as active and you will receive even more rubbish.

Instead, forward the text to 7726

Spells SPAM on multi-tap keyboards.

Include the number that sent it to you. If enough SPAM reports are made to this number, which ever network you are on, the sending SIM will be DISCONNECTED.

Fight back!

Here is the full article.
Original MSE article.