I also received a message from this number claiming to be 53 bank.  I called them and they asked for my account number. I told them I did not know it. Then they asked for my social security number. I told him I did not know it and promptly hung up.

A call was left on my answering machine claiming to be Fifth Third Bank.  It stated that I should call regarding my bank account.  I was not familiar with Fifth Third Bank.  Thus, I definitely didn't have a bank account with them. As you can see, I was immediately suspicious.  Since my number is restricted, where and how do you think these individuals are getting the information.  

Got a voice message from 800-421-9543 saying I needed to call for an important message from Fifth Third Bank. When I called I got a recording that asked me to enter my account number. If you don't know it, you are to enter your Social security number. That request right there convinced me this is call was a ruse for identity theft. I hung up.

800-421-9543 is a fake bank phising scam

Ditto.
Out of curiosity, I "played along" and provided the automated machine with a false account number which it accepted.  It then asked for my SSN for which I provided another false number.  It then asked for my phone number.  After all that (obviously, none of it could've been successfully verified) a human answered, who began the drill all over again.

recieved call from this number yesterday. total scam.

Called that number 1-800-421-9543 and got Raul. SCAM!!

Received a call from this number.

FYI, I have received two messages from this number, both on my work phone and both on Sunday.  Upon calling the number they answer as Fifth Third Bank (who is my personal bank).  They asked me for my name and account number neither of which I would give them.  On top of my original suspicions the phone connection I had was terrible.  I refused to give them any info and quickly afterward called my local branch.  The branch confirmed there were NO issues with my account.

Twice in the past week I've received a voicemail message on my business phone from 5/3rd bank (which is my bank) asking me to call 1-800-421-9543 regarding a problem with my account.  I'm always suspicious of scams though.  The first time I got the message I called my bank on their actual 800 number that is given for customer service on their website...they verified their weren't any messages on my account.  Then I called 800-421-9543 out of curiousity...they asked me what number I was calling from first.  Then for my name.  I told them I had reservations about giving any personal information and with that she hung up on me.

I suspected and am now thoroughly convinced this is a scam...DO NOT give them any information.

mystery how they got the number....call all the time...never stop calling, even on Sundays!

I got a call on Sunday from "our bank.I told her the company owner didn't work on weekends.Then I got a message last night to call our bank about a very important matter.I called and it was answered with our banks' name She asked for the number I was calling from.Then she asked for the account number.I refused to give it to her and she told me"never mind,the problem is fixed".I asked her how it got fixed magically without the company owner and during weekend hours when banks are closed.