I just put my husband on the phone and he speaks in his native language, which sounds annoying anyway. They never call back. :) I have made up a bunch of different sounds that could be taken for a foreign language. They never call back.
Go back to the old whistle trick. Blow a whistle into the phone. They will not call back.
Got a missed call from this number (458) 201-0431. When I called them back they ask for me by name and advise it was in reference to money I owed the IRS. I told the IRS money and they disconnected the line. I called back and spoke to someone else an they advised their company name is Assistant support system and that they help people who owe debt to the IRS, credit card companies, etc... I asked him to take me off the call list.