They all and don't leave a message. I called back and it has many extensions and depts to choose from. But it's clear they are either a collections agency or a phishing scam.
Received a call from this number today. They left no message. I did not call back. I'm already dealing with a credit card fraud situation right now. This only adds to my anger and upset.
Legit call. This was Morgan Stanley (or more likely, a vendor working on their behalf) calling to verify potential fraud activity on my debit card. As I didn't recognize the number, I didn't answer, but they left a voicemail. After listening to the message, I called back the number printed on my card, and the reps verified they were trying to reach me regarding unusual activity. Verified the transactions (plane tickets on Qatar Airways) were indeed fraudulent. Bank reversed transactions, blocked old card, and Fed-Ex'ed me a new debit card overnight.