Also getting spam phone calls from this telephone number.

This number started calling me on July 5, 2012. I always research random numbers when they call me and I can see that the individual above me @Kevin started getting calls a few days ago as well. I don't pick up, and they let the voicemail start to record and then they hang up. So now i have several 3 second empty voicemails that i have to delete. It's inconvenient.

Not sure what these people want, but now it's clear we are on some kind of call list.

Same as above. I've got a hunch it is a robocall from Comcast. They called me for an upgrade 3 days ago.

You are correct!   This number has been calling me alot and I finally called them back and they want you to upgrade your cable.  It actually a pretty good deal.

This dang number has been calling me for a few weeks.  I don't answer numbers I don't know, and they don't leave voice mail.  Finally got fed up and answered and it was supposedly a Comcast guy like some else mentioned.  Told him I wasn't interested, he asked why, etc.  He said if I change my mind to call him back at this or some (720) area code number.

Usually when Comcast calls me (i.e. forget to pay a bill!) they call from an (866) number, so I am/was suspicious about this.  And why wouldn't the callback number be 1-800-COMCAST or whatever they are...?  I looked this number up on the white pages lookup and it said it was a mobile phone...

Kinda of suspicious if you ask me, but may be legit.  Don't worry, I called him back and gave all of my credit card information, so I am looking forward to my Comast upgrade... Kidding.