they just hang up

They don't have a do not call list. But scammers love it when confused suckers call them back believing otherwise.

I didnt pick up the call. Called them back. An automated message said that it was a telemarketing call. It said "If you do not wish to be called press 1 to add your number to OUR DO NOT CALL LIST". I entered 1. It then said "Enter your 10 digit phone number after the beep". But there was no beep. Looks like they do not want anyone on THEIR DO NOT CALL list.!