I've been getting calls from this # all morning on my business switchboard.  No one is on the other end - complete silence.  After 10 - 20 seconds, the call automatically disconnects.  When I call back, I get an automated "Concentric" message stating that person I'm trying to reach is unavailable and to try again later.

I keep getting a call from this company and they let the phone ring 4 xs and then leave no message.