DT, I also worked with a HFC system that provided voice services along with video and cable modem in Calif. As you said, all of the activity in phone over HFC has been a circuit switched network arrangement. The equipment used to date has been telco digital loop carrier systems that were RF adapted to become Host Digital Terminals at the central office / headend. The HDT is equipped with RF modems that use QPSK to modulate the baseband digital signals for transmission over the HFC system. This stuff gets pretty expensive when you add it on in addition to the switch. No wonder Time Warner, like most others who have offered voice over HFC to date, kept deployment to a limited level. Cox has been very ambitious and quite successful in Southern Calif. and some other areas, especially where they bundle services in multi-tenant buildings.
In 1997, Lucent quit making its voice over HFC system called HFC-2000 (adapted from the SLC-2000). Nortel has pretty well refined their Cornerstone HFC system, and it seems to have a following with many players in North America and beyond. I don't know if ADC ever got rolling with its voice over HFC system. As far as the other vendors like Motorola, Phillips, GI, SA, they all came up with fairly simple versions of voice over HFC equipment, but they ran into tough times because of low volume demand. Also, they lacked the inside track on keeping up with the all important switch interfaces for the HDT, something that gives Nortel an edge over the others.
The closest thing I have seen to an inside track on IP telephony combined with a cable modem comes from Com21. Although they are banking on a data services cable modem to gain an initial market position,the long term view looks like a multi-services digital gateway that would support voice over IP. Regardless, I agree with you that IP voice over cable systems is not just around the corner. In a couple of years I think we will see some beta versions, and a year or two after that some decent sized initial deployments. My guess is that the vast majority of ATT+TCI customers will have to wait at least 5 years after the merger to get a chance to sign up for VoIP service over HFC networks. It might take so long, that AT&T shareholders would stage a coup d'etat against the debt and red ink that would pile up in the interim.
Ray. |
