Dead air when I picked up; guess my lack of noise didn't trigger the computer to switch over to a human. Called number back and the recording said it was directing my call to the voicemail box for (what sounded like) "DT Services <something>". Added to the block list.

Oops... I meant to say "DT Client <something>" but gave it another listen, and it was "DT Client Services CO".

Received 2 calls from this number on 8/13/16 around 11:30am and 1pm in Denver.  No voicemail was left after the first call but a message of dead air/silence was recorded after the second call.  Caller ID said "Out of area" despite a local area code.

I got the same calls at approximately the same times.  Don't have a clue who is calling or why.

Today, Saturday, August 13th, I received the following telephone calls from 720-808-1591 at the following times:
10:45 AM/12.32 PM/1:59 PM/ & 3:19 PM. They say it's from DT Client Services. Whoever they are, they are going to have to call it QUITS. I don't know who they are! This is disturbing!