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...