Who called from 3147664298

"cannot call it back" means the number is spoofed  https://en.wikipedia.org/wiki/Caller_ID_spoofing  and your caller should be treated as hostile.

This number is *NOT* Verizon Wireless because it's not listed on verizonwireless.com as a contact number.
Don't believe there is any such animal as Verizon Financial Services either.

I'm getting calls from this number & they don't leave a message. I do not know them & unable to call them back

They are calling because you have an account in collections owned by Verizon.  It may originally been with another carrier that is out of business like Altell, for example, but is now owned by Verizon. It may be up to 10 years old. This is not regarding a current Verizon Wireless account that is past due. You are probably receiving notifications by mail as well.

It'sVerizon Wireless automated reminder system. Your bill is past due.