[asterisk-users] Randulo: An open suggestion for the VOIP users Conference

[mgraves at mstvp.com]

On Thu, 07 Aug 2008 00:28:29 -0500, Karl Fife wrote:

>Example:   Last week there was talk about Polycom's "HDVoice"
>technology, and the term was being used interchangeably with G.722.  In
>fact there are important distinctions, but someone listening might
>presume that the information was correct and leave short-changed.  There
>are other examples even from last week, one involving someone's claim
>that there's not a way to pick up a phone and directly interface with a
>voice recognition directory application without needing to press some
>digits first.  As it turns out, it's easy if you know the trick.  
>
>Id' be happy to put my money where my mouth is and kick off this
>Friday's show with these examples & any others I'm not remembering at
>this moment if you think it would be well received.  Perhaps others will
>do the same.
>What do you think?  
>
>Thanks!
>-Karl Fife
>
>If you want to discuss this off-list, you can email me at
>voipucsug at kfife.mailworks.org.
>
>p.s.
>As it turns out, HDVoice CAN use G.722, but it can also be overlain onto
>other codec's such as use G.722.1 and even G.711µ [sic].  That's right,
>you can have an "HDVvoice" call over the PSTN using G.711, using a
>special companding overlay on top G.711.  As I understand it, the two
>HDVoice compliant endpoints (Polycom, Cisco & others that license the
>technology) have an in-band (but inaudible) handshake, and then begin
>applying the proprietary companding overlay which extends the dynamic
>range of the audio.  It sounds great even though the underlying codec is
>not a wideband codec.  Certainly the sound is not as good as HDVoice
>over a modern adaptive-transform codec like G.722 (1987) or even better
>over G.722.1 (1999), but it's definitely a big improvement over the
>"Toll-Quality" (Read: AM-Radio-Through-A-Pillow) that we're all used to,
>and it is not dependent upon having a pure-IP connection involving ENUM,
>DUNDI, or other non e.164 namespaces such as SIP URI's, ITAD Subscriber
>Numbers etc.  In my opinion HDVoice is it's a brilliant transition
>technology.  
>

Karl,

This is very interesting. Did you see that Polycom made G.722.1
available through a royalty free license earlier th
week?

http://www.polycom.com/usa/en/company/news_room/press_releases/2008/2008
0805.html

In tinkering with the three phones that I have (ip650/550 & Siemens
S685IP) they all support only G.722. At least according to the
datasheets even the Polycom models don't handle G.722.1 as yet. 

Mind you I haven' gone so far as to use Wireshark to analyse the
traffic. Just measure the bandwith used across my router and note when
the phone indicates "HD" engaged on the line button.

Do you know if the companded processing you mention is implemented in
the Soundpoint models? Just from the sound of it it could improve S/N
ratio, be perhaps not frequency response. Still, it's good that they
can improve a call over the PSTN.

So, perhaps there's more to HDVoice than just G.722. Even so, G.722 is
all that I have experienced of HDVoice in their current Soundpoint IP
phones. I suspect that some of their technology is only deployed in
their larger conferencing systems, and not in the Soundpoint lineup.

Michael
--
Michael Graves
mgraves<at>mstvp.com
http://blog.mgraves.org
o713-861-4005
c713-201-1262
sip:mjgraves at pixelpower.onsip.com
skype mjgraves