AT&T CallVantage VoIP calls blocked

August 12, 2004

Some VoIP calls being blocked | CNET News.com

Cnet.com has reported that some users are having issue receiving inbound calls. This has once again raised the issue of whether or not cable broadband companies are blocking VoIP calls.

I discussed the potential for network service providers to block VoIP traffic in my Vonage Outage Part 2 blog entry. Damn hypercompetive bastards!

A TMC VoIP Forum poster also commented on not being able to receive inbound calls, as seen in the thread titled "AT&T Call Vantage Sucks"

According to Cnet, AT&T is using a non-standard VoIP port - port 69 to be precise. Most VoIP providers use the standard SIP port - 5060. Apparently, port 69 was used by the MSBlast virus, so many ISPs are now filtering this port.

When will AT&T learn? Stick with the standards and don't go "all proprietary on us" and you'll be all right...



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» AT&T CallVantage Outage from VoIP Blog - VoIP News, Gadgets
I meant to blog the AT&T CallVantage outage this morning, but wanted to confirm some info with one of my sources first. Apparently, this past Thursday (1/13/2005), AT&T CallVantage experienced an outage in at least Virginia and parts of New... [More]

Tracked on January 17, 2005 4:04 PM

Comments to AT&T CallVantage VoIP calls blocked


  1. M. McIntosh :
    September 10, 2004 9:48 PM

    At&T is shipping a new TA for the CallVantage system on September 16th. It will use port 80 instead of 69. This should take care of most problems with port blocking, unless the ISP in question is doing it deliberately to give them problems. Since that would be cause for a court case, I doubt that will be a issue. Port blocking by ISPs is usually to deal with Viruses. The MSblast virus uses port 69.


  1. don :
    January 13, 2005 6:48 PM

    Have CallVantage here in NJ. System is down. Sent an email to them and response is there is inclement weather in Kansas City which knocked out the system.


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