Consistently get a blind - dial "Unknown Name" with 321-304-9999 as the id.
Pressing any button seems to put me in a queue to talk to someone, but never seems to go thru.
I'm on the do not call list, which would be enforced by the government, excepting that the entire bureau has been gutted by the last administration. Not to worry though... when I find the location...
This is definitely a SCAM! Claimed to be my 'Card Company', and asked for my card numbers, expiration dates & such, saying I could lower my interest rate to 6.9%. I refused, saying I had no way of knowing who they are. They hung up.