Who called from 9514916348

I called the # back and got the hi pitch squeal, might be fax machine

When I answered, I could hear voices in the background (like a call center?) but no one spoke.  After I hung up, I got two more calls in quick succession from this number, but no message was left.

Its California Image and, Diagnostics. That's the Ph Num their Computor call's from to remind you of your Appointment.
Its not a Telemarketer.

Caller id It says pacific dog is calling. Keep telling them to take is off the list but they don't. Located in homeland calif

I too received a call from (951)  491-6348, it is California Imaging & Diagnostics calling to remind me of my appointment.