Who called from 5519962000

Received multiple calls but I didn't have my phone. No voice mail message and researched number came up a hospital in NJ but I don't know anyone in a hospital. Wrong Number?

another call from 551.996.2000........doesn't look familiar......I don't answer it......plain and simple.....no message....

Receieved call from this number shows up as HACKENSACK  UNIV.No message left.

This is a legitimate exchange for Hackensack Hospital in NJ.

I never answer numbers I don't know