THIS COMPANY IS AN EXAMPLE OF WHO THE GOVERNMENT SHOULD PROSECUTE
They call all the time - the keep changing number to prevent blocking.
BLOCK THESE FAXHALT’s NUMBERS:
720-639-8574
303-732-3619
720-386-2720
720-386-2808
720-386-2864
720-386-2884
720-386-2947
720-449-3655
720-639-7843
720-639-7862
720-639-7878
877-280-8277
They use different phone numbers to circumvent blocking.
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Called 2 times within a minute.
720-639-8574 called landline (fax) on June 2, 2016 at 9:05 am.  BLOCKED immediately.
720-639-8574 called landline (voice) on June 2, 2016 at 9:04 am.  BLOCKED immediately.
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720-639-7862 FAXED 2 times on March 2, 2016 at 9:12 am.  Caller ID = FAXHALT.COM.
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PRIOR HISTORY:
720-639-7843 FAXED 2 times today. (Lucky my fax was unplugged, but caller ID caught it).
FAXED Jan 20 at 9:17 am.  Caller ID = FAXHALT.COM
FAXED Jan 20 at 9:04 am.  Caller ID = FAXHALT.COM
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Their website says “Sometimes faxes are sent by mistake. FaxHalt provides a way for you to stop receiving unwanted faxes. Simply enter your number below or leave us a message at 303-732-3619, and we will permanently add your number to the do-not-call list. Most requests are completed within 24 hours, however, in some cases, it may take up to 72.”
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They are the ones guilty of sending UNWANTED FAXES.
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Prior history:
720-639-7878 called (FAX LINE) Oct 8, 2015 at 9:19 am.Caller ID = FAXHALT.COM
Unwanted Fax = their website says “FaxHalt provides a way for you to stop receiving unwanted faxes.”
Yet they are the one creating unwanted Faxes.
BLOCKED

I dealt with a similar situation with a previous number. I started receiving what I believe were fax calls throughout the day and late at night (2:00 am & later) . Because of it I subscribed to caller ID and logged about 40 fax calls in one day.  I attempted to call the number & discovered it was spoofed. In the end I was forced to change my number.

FAXHALT
Posted in: http://800notes.com/Phone.aspx/1-720-386-2759
http://800notes.com/Phone.aspx/1-720-386-2808#p900513256179935979
http://800notes.com/Phone.aspx/1-720-449-3655/2
http://800notes.com/Phone.aspx/1-720-639-7927
http://800notes.com/Phone.aspx/1-720-639-8574
I got home today and there was a call from this number. The Caller ID read FAXHALT. So I searched on the web and came up with a one page site that says if I were to receive faxes in error I should enter my number and they will remove it from the call list. No company address, no information. Just one page: http://www.faxhalt.com/

Sounds like a phishing expedition to get live fax numbers to send unsolicited faxes to.
Whois Info:
WARNING! WARNING!
New Site With Limited & Hidden Information
Site is Singapore based , But The Real Location Is Being Hidden

Summary:
Website: faxhalt.com
Title: FaxHalt

Domain Age: 280 Days
Website Speed: Slow

Organisation: WHOIS PRIVACY PROTECTION SERVICE, INC.
Owner: WHOIS AGENT
Owner Address: PO BOX 639 C/O FAXHALT.COM
Owner City: KIRKLAND
Owner Postcode: 98083
Phone Number: 14252740657
Phone Type: geographic :Bellevue, WA Allegiance Telecom Of Washington, Inc.
Email:

Owner Country : Hidden
Website Location : Singapore

Probable website origin :-
87%; Unknown
7%; United States
4%; Singapore
2%; Australia

Notes:-
[Alert Result] The owner of the website is using a service to hide their identity
[Alert Result] This website is 280 Days old
[Alert Result] The website expected life (365 days) is relatively short.

Owner, Administrator and Technical Contact:
Name: WHOIS AGENT
Organisation: WHOIS PRIVACY PROTECTION SERVICE, INC.
Street: PO BOX 639 C/O FAXHALT.COM
City: KIRKLAND
State: WA
Postalcode: 98083
Country: United States
Telephone: 14252740657
Phone Type: geographic : Bellevue, WA Allegiance Telecom Of Washington, Inc.
Email: JNJWDQVRQ@WHOISPRIVACYPROTECT.COM
Registrar: ENOM, INC. (are we REALLY that surprised here?)
Web : http://www.enom.com
Registrar Country: United States

Server:
Ip Address: 119.81.76.81
Hosting Service: "SoftLayer Dutch Holdings B.V."
Hosting City:
Hosting Region:
Hosting Postal:
Hosting Country: Singapore
Domain Created: 2014-04-25T03:08:00.00Z
Domain Expires: 2015-04-25T03:08:00.00Z
Domain Life:
Est Value: $
Ping: 1486
Speed: Slow
Network Name: Asia Pacific Network Information Centre
Network Country: Australia

Named Servers:
Nameserver 0 IP: 216.12.221.37
Target : ns2.zoom-dns.com
City : Jurong East
Region : 00
Country: Singapore

Nameserver 1 IP: 216.12.221.36
Target : ns1.zoom-dns.com
City : Jurong East
Region : 00
Country: Singapore

Note that the true web site is hidden and that Singapore is mentioned.  This is certainly some place you want to stay away from at all costs.
Report it to the following authorities:  https://complaints.donotcall.gov/complaint/complaintcheck.aspx?panel=2
https://www.ftccomplaintassistant.gov/#crnt&panel1-1
Also file a complaint with your State Attorney General's office.
List of State AG’s offices:  http://consumerfraudreporting.org/stateattorneygenerallist.php