For a cell phone, some already have call blocking, if not, there are free apps on the web that will work for some. You can google this. If you have a smart phone, there is a free app called call control. Iphones appear to have apps also. Another one is called Mr. Number.
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.
Report your callers here, not just to the DNC alone:
Wasn't a call (or a website?), only a SMS Text. So DNC, etc. is of no help. I can block specific phone numbers on my WP, but not texts. The message was exactly as shown, your response is non-applicable and incorrect wrt AT&T.
It was on AT&T automated system and the spam text can be forwarded to 7726, but it did no good because the sending number could not be identified, i.e. 323607360221734, even tried the number within the text body 13128838186, but the automated system knew that number wasn't used to send the text. So the final at&t system response was to contact customer care for additional help.