I got a call from the same number, using the same "Please hold, it is important that we speak with you," baloney.

Fyi, an established institution like Mt. Sinai is unlikely to have a 786 area code for one of its land lines.  786 is generally for certain cell phone services and newer (as in the last few years) land lines.  Mt. Sinai's listed contact numbers have the 305 area code.

Just got a call from 786-478-3052. Answered it and it took a while for a female to speak. She then asked for some persons name which was not mine. I told her wrong number and asked her where she was calling from? She indicate, Mt Sinai Medical Center Miami. (Collection Dept).

It is  Mount Sinai Debt collector.  And locally in south beac 786 is a landline number as both my home and place of business landlines have the 786 area code.  This is the debt collection service for Mt. Sinai so it doesn't mean it's actually in the same building or area.  It's a contracted service.