Unless you deal only in cash, never having had either a bank account or a credit account, you will find it all but utterly impossible to avoid these calls. When the Congress authorized the creation of a "no-call registry," they exempted charitable and political solicitations (granting charities the exemption to give themselves political cover for their own fund-raising) and any company with whom you have previously done business. For most of us, this means the credit hawkers -- most of which are either owned by or partnered with banks. The banks regularly share their lists, and vice versa.
I look at the CID when the phone rings; if I do not recognize the name or number (the ubiquitous "unavailable" gets an immediate hang-up), I either answer it saying "hello" followed precisely one second later by a second "hello." If there has been no response by the last vibration of my ending vowel, I hang up -- or I simply let it ring. They almost never go past three or four rings, knowing that the average voice mail will pick up after the fourth.
You can't win. You can ask the bastards to remove you from their list, and they supposedly are obligated to honor your request, but I got tired of asking them to do so without result. It is no where near as bad now as it used to be before the minimal advantage of the "no-call list." It is still worth adding your numbers to that FCC site.