The cable industry has a steady, if unspoken, roadmap for HD voice delivery. Three steps to HD voice are already taking place today with the fourth under active discussion among the big cable companies.

Step one has been the rollout by CableLabs (News - Alert) -- cable's standards body -- of PacketCable specifications for delivering SIP and ENUM services down the existing cable infrastructure, specifically the PacketCable IP Interconnect, and PacketCable HD voice with DECT (News - Alert) specifications standards. With the latest document released on June 30, 2010, the PacketCable IP Interconnect package provides ENUM lookup between phone numbers and routing of those SIP sessions "to the target destinations which may be served by the cable operator's own internal network or by a session peering partner."  

Under the PacketCable Applications suite, the latest version of the PacketCable High Definition (HD) Voice specification clearly links the future of HD voice on cable to the international DECT CAT-iq standard -- this is no big secret, since CableLabs has been throwing out a lot of love for CAT-iq over the past year.   Currently, PacketCable HD voice is linked to the CAT-iq 2.0 standard and CAT-iq 2.0 hardware certification is expected to begin in September along with a second "plugfest" to verify device interoperability.

Which brings us to step two of the equation: residential CPE. For a MSO, customer equipment is always a tricky thing because there's typically a large base of deployed equipment, so you end up having to balance end-of-life of deployed gear with upgrading new gear and making sure the new gear is firmware upgradable -- and doesn't break anything currently deployed by accident. 

There's not really a clear picture as to who has what HD voice capable gear out in the field today waiting for a firmware upgrade, but it is clear that there will be more gear adhering to the latest PacketCable and CAT-iq 2.0 standards by the end of the year. 

Step three, moving out of the residential world into business services, it's all about SIP trunking. If you can deliver SIP trunking, you can put customers on a hosted VoIP solution and supporting HD voice becomes a simple codec/handset feature.   Optimum Lightpath (News - Alert) is already supporting HD voice in New York -- parent Cablevision tends to be on the leading edge compared to its MSO peers -- and larger companies are likely to follow suit in 2011.

Step four is the SIP interoperability issue, being able to exchange calls directly without touching the PSTN and "downgrading" to narrowband.   At The Cable Show in March, Comcast (News - Alert) EVP and CTO Tony Werner cited one of the reasons for cable companies to directly exchange voice calls was to insure better end-to-end quality of service and to support advanced services like HD voice.   Cable CTOs are talking about moving calls directly among themselves, but there's been no Big Shift -- yet. The PacketCable IP Interconnect standards mentioned above will facilitate some movement on this issue, but the cable people tend to hold their cards tightly in terms of when.