Who called from 5715217493

Calls, leaves no message...just dead air for 20 or 20 seconds.

I got 3 messages from this phone number last night (Dec. 2, 2014) at 4:34 and 4:35 local time (EST).  A little bit of background noise, maybe a breath heard, but no spoken message.   The messages were 43, 53 & 90 seconds long.  The caller was identified as "DELTEK" in my caller ID.