Two calls 30 min.apart. If I can not iidentify the caller by an actual name or recognizable phone  number I never  answer.
They usually let the phone ring three of four times so you have to be patient and control your natural curiosity. Of all the
blocking systems I find the "DO NOT ANSWER SYSTEM" workd the best.

Constantly getting calls from "FAX GLOBAL" on a residential non-fax line.

Never a voice mail, I gather as others have said it's a fax machine. Wonder what they are trying to scam anyone with a fax machine out of.

Yup called, said FAX GLOBAL, answered and heard what sounded like harsh Indian voice, then nothing.  What happened to do not call list HUH?

Yes, I get this call every day but I don't answer it.  I will tell you simply......  you can't make donations or you will be on these damn caller lists or "sucker" lists for ever.  I made donations to several charities and now I am besieged with these endless beggars.   Very frustrating.  I don't know who FAX global is and I don't ever answer the phone anymore.  

Missed call on home #. Called back.  Got "this number is not in use" message.  Blocking #.