Who called from 6144126258

I just got a call from this phone number. They did not leave a message. When I called back, it was obvious it was a call center: After a bunch of noises, a man with a very low voice said, "Hello?"
I heard that voice before--MANY TIMES. They use different phone numbers to call from. I hung up.

Man said "hello" seven times, then hung up!

They hung up on answering machine ... again.

Called but left no message.

After a long pause.. a guy came on identifying himself as calling for The National Fire and Police fund....