You can not!! They are computer dialed and once they get a hold of real phones numbers, they resell your number to others so those Scammers can bother you too. Either do not answer TOLL FREE CALLS or buy a phone that blocks calls you do not want.
I got a call from this number on a Saturday morning. I never answer a call on my cell if I don't know the number. They did not leave a message. I wish I won a cruise to the Bahamas.