Who called from 3176149857

Message left for Katherine.  I didn't call back because what showed up on my id was strange.

did not answer unknown number.
no id came up

Got a call from 317-614-9857.  Caller ID says Zotec.  They have called several time and there is no one on the phone when I answer it

This number is from a company named Zotec, which is a billing company for radiological services.  
If you had any radiology services from ANY hospital and did not pay within a month of recieving the bill, they will call you to try to retrieve the payment.

I received a call supposedly from a physician billing office . but after following their instructions and waitting over 4 minutes I hung up.  I have not received a bill from them but they're calling me??