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.
Report your callers here, not just to the DNC alone:
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.
By State DNC lists:
http://800notes.com/res/DoNotCall.aspx
I've been getting the same kind of calls from this nut, call and won't speak, and texting weird pictures of women being tied up and another of a dead man... It's irritating, but then it got real, when he mentioned me by name, so I blocked the number and I'm on my way to the police station...!
Malicious caller identification, activated by Vertical service code Star codes *57, is an upcharge fee subscription service offered by telephone company providers which, when dialed immediately after a malicious call, records meta-data for police follow-up. Remember to file a police report for each use - law enforcement will only act on the trace once a formal police report is filed in regard to the call.
Malicious caller identification facility, also called malicious call trace or caller activated malicious call trace, when subscribed or enabled, works by allowing a phone call recipient to mark or flag the preceding phone call connection as malicious (i.e. harassing, threatening, obscene, etc.) The phone system will then automatically trace the call by flagging station to station billing and routing data including start and end times. The call trace is not dependent upon call duration (as envisioned in dramatic movie plots) and will record all meta-data regardless of source conditions - even if the call was made from a silent number, payphone or a number with caller identification disabled. To protect privacy the resulting trace data is only made available to law enforcement.
How the user activates this feature depends on their phone system — generally it is either in-band-signaling DTMF sequence such as the *57 Vertical service code or a special button attached to their phone generating an out-of-band signal. For analogue services, many exchanges will interpret DTMF sequences to activate POTS. Digital services, such as ISDN or GSM, enable the CPE to activate MCI via out-of-band signaling. Often with PABXs with analogue phone connections, the PABX will interpret the DTMF and then activate the out-of-band signaling.