I keep receiving a call from an unknown number, they don't leave a message and I get a fast busy signal when I try to return the call. Frustrating!

Calls even though we are on the Do Not Call list! No one is there when I answer, and does not leave a message on answering machine.

this number is a medical company trying to sell you insurance.

received call noone responded. tried to call number back and got to check  number and try again

Got a call from this number but no one responded.