Unfortunately many non-POTS VoIP devices do not support wideband codecs either. My Philips VOIP841 skypephone doesn't.

People still repeat that old chestnut about VoIP not matching POTS quality. My experience with Skype and SVOPC is that it is far superior to POTS, let alone cell phones, specially in communicating subtle nuances in timbre.

In fact, Polycom's very first wideband product was a conference phone called the VTX-1000. It's designed to connect to a POTS line, yet it truly is wideband capable.

When it dials the remote party it sends a few tones to try and determine if the far end is also a VTX-1000. If so, then it creates a data connection (v.32) and passes the call data as if it were a apri of modems connected.

Since the VTX uses a low bit rate codec (G.722.1)the call can be sustained in < 56 kbps and still have a wideband connection.

If the far end is NOT another VTX then the call is handled as a normal G.711 call, merely with superior hardware (transducer) capabilities.

So, wideband cann effectively tunnel through the existing PSTN. But is this a model that would work more widely? Or is this simply a way of making end-points more costly with little benefit in most cases?

Mike, Yes as you sate here and have pointed out to me in another context that VTX-1000 uses the exact procedure I describe here. It just supports my claim that one can have HD voice in PSTN as well.

This is the only model that will work in a "stupid" network and PSTN is a stupid one. I am not sure that the phones will be expensive one. I think it can be added to DECT-class phones with not much appreciable cost. In my opinion this is better than trying to improve the network quality globally.