"What everyone is actually *selling* commercially, except for cable providers, is *not* VoIP; it's a subset of that: VoN; Voice Over Internet; where the IP transport *goes over the public internet*, and through whatever exchange points may be necessary to get from you to the provider.
Hmm, I don't know if this is a useful distinction. I do know that is not the common usage for VoN. VoN is more commonly understood to be Voice over Network which is a superset of VOIP rather than a subset. http://en.wikipedia.org/wiki/Voip http://bit.ly/f9u08K
Cable companies are selling you *one hop* (maybe 2 or 3; certainly not 12-18), over a link with bandwidth protected from whatever may be going on on the Internet IP link they're also selling you; and which is therefore guaranteed to have better quality than whatever "VoIP" service it might be competing with."
That also depends. While the most common method for cable operators is Packet Cable using dedicated links to and from the softswitch/session border controller that is by no means universal. Here are two companies I know of that specialize in selling pure SIP solutions, which are often back hauled across the public Internet. http://xcastlabs.com/ https://www.momentumtelecom.com/
I wasn't suggesting QOS. I was suggesting *there's a completely separate pipe*, on non-Internet connected IP transport, carrying only the voice traffic, directly to a termination point, which is dedicated from the triple-play box and nailed up.
Are you suggesting that's *not* how it's being done in production?
In some cases, there is a dedicated connection to the underlying MGCP/SIP network and in others there is not. In some cases there is an MPLS connection with QoS over the public Internet and in others there is prioritization at all. (I don't recommend the latter, but its usually an economic issue.)
Cheers, -- jra
-- Scott Helms Vice President of Technology ISP Alliance, Inc. DBA ZCorum (678) 507-5000 -------------------------------- http://twitter.com/kscotthelms --------------------------------