http://www.prnewswire.com/cgi-bin/stories.pl?ACCT=104&STORY=/www/story/12-12-2005/0004231957&EDATE=
Unlike traditional Voice over Internet Protocol (VoIP) offerings that
run on the public Internet, Comcast Digital Voice calls originate and
travel over Comcast's advanced, proprietary managed network. Because
Comcast Digital Voice is a managed service, Comcast can make sure that
customer calls get priority handling.
Comcast doesn't have good public Internet access? That's a shame. I
commend their bravery in admitting that only their internal network
is advanced.
</sarcasm>
John