I got a call from this number - when I answered, an automated message said "You have a call from [silence]. If you accept, press star (I think it was star anyway). If you want to leave a voice message, press 5." So I pressed 5 and then it said "to join the call, press star" and when I did that the phone hung up.

What the heck?  So I called the number back and it rang forever.

I got a quick call from the number later on in the day that hung up real quick. So I called it back again and a woman answered in Spanish. I speak Spanish so I told her I got a call from her earlier in the day. She acted rather paranoid and evasive - suggesting that it must have been a wrong number. It left me rather suspicious.