Got a call from this no yesterday, I didn't pick up and no message was left. I'm  303 number but don't know anybody in Georgetown so let it go.

7:31 pm got call from this #. Didn't recognize, didn't answer. No message left. Don't know anyone in Georgetown.

I too am in CO. I get a call once a week from this number on my ATT cell phone. Very annoying. One ring and hangup has been the pattern.

This is a robo call for a rewards redemtion $100 gift card. Msg states that you have recently visited an affiliates website and they would like to reward you with a $100 redemption card at places like Walmart/Best Buy etc.

If you press 2 you will be removed from their call list.  

If you press 1 they will transfer you to a live person who will tell you about the redemption card offer.

I pressed 2.

Same as every one else. Received a call 3/24/14 at 11am on my cell phone. Did not hear a ring, no MSG left. Not that it does any good, but I'm on the National Do Not Call for both landline and cell phone.

3 calls from this number in the last week. Also only had one ring, also I'm in CO with a 303 number. Local robocaller?

Got a call on 3/17/14 at 7:50 p.m.  Didn't answer. Rang only once.

I've received 2 calls on my cell phone from this number - one last Thursday and again on Saturday.  I didn't answer either call because I didn't know the caller.  However, after reading this blog, I've added it to my contact list as Unknown Caller-4 and blocked it - just as I have for Unknowns 1-3!

2/3/14 - 8:36 PM called for not even a ring on my side. All information I can find is already on this page.

I noticed a missed call but they left no message. I'm from Colorado and have a 303 number. Hmm.

Got a call from this number at 12:11 pm on Jan 31st. It rang twice then disconnected. I live in CO so thought it could be someone I know, but didn't get a chance to pick up. Glad I didn't!

I got a call from this number on my cell at 4:35pm on 1/28/14. I didn't see it until later, so didn't answer the call (I was in a meeting-phone was on mute). CID says it's from Georgetown, CO, but when I Googled the number, I also see Idaho Springs, CO listed. I live in CO and know where both those towns are (about a half hour drive between them), but I don't know anyone who lives in either town anymore (not for a very long time now), or why any business in either town would be calling me.
I read this at callercenter.com:
Its exchange 900 is managed by LEVEL 3 COMMUNICATIONS, LLC -.
The number is currently on switch number DNVTCO56DS2.

My guess is it's a robo call, possibly a spoofed number. Likely, someone/thing calls from this number and won't leave a message, hoping the caller will return the call so they can collect the return caller number to put on a list that is then sold.  

Opal Events ? Healthcare ?

someplace noted as Healthcare Seminars -

Called last night after 9pm: one-ringer, no message. Didn't answer as I don't already know the number; my people know to leave messages anymore. Don't know anyone in Clear Creek County anyway.

Received this at 9:05 am on cell phone, left no message. No idea who from. An online phone search engine showed it a land line coming from somewhere near Georgetown, Clear Creek County, Colorado.  303 is a Colorado area code but I've never seen a 900 prefix before associated with a private phone number.