The number they use us a phantom number for caller ID, so it isn't the real Phone number. That's why you can't block it. My suggestion is, (if you have the option) set the ring tone for this caller ID to no sound. I recorded a custom ring tone of dead air with the mic under my pillow.
There is a pause after you answer, indicating an autodialer that is then routing your call once you pick up. The person that comes on the line is in a boiler room (can hear other voices behind). Says she is with "East Valley Financial" and can reduce interest rates on credit cards to 5%. Wants the answer to 4 simple questions. The first is: do you owe more than $7,000 on credit cards. When questioned about their connection to credit card companies, got evasive, but tried to stick to the script and get answers to the questions.
When asked about what it would cost, she wouldn't answer, and stammered about a bit before getting back on script.
They are obviously selling financial services, but the person on the phone is only the front for the real heavies that will call you later once they get the answers they want to the four questions...