Subject: RE: [Ecrit] Audio Codecs for 911 CALLS.

From: "Stark, Barbara" <[email-masked]>
Date: Tue, 8 Aug 2006 10:51:57 -0500

BCP says:
   12.  A normal SDP offer SHOULD be included in the INVITE.  The offer
        SHOULD NOT include compressed audio codecs, although a wideband
        codec offer MAY be included.

   Note: Silence suppression (Voice Activity Detection methods) MUST NOT
   be used on emergency calls.  PSAP call takers sometimes get
   information on what is happening in the background to determine how
   to process the call.

Barbara

-----Original Message-----
From: [email-masked] [mailto:[email-masked]]
Sent: Tuesday, August 08, 2006 10:34 AM
To: Brian Rosen
Cc: [email-masked]; 'Karihaloo, Ujjval'
Subject: RE: [Ecrit] Audio Codecs for 911 CALLS.

Hi, 

I certainly agree with below, G.711 is a MUST for both ends -- it is the
common denominator supported by virtually everything in one way or
another (one of those possible ways being via transcoding).  To avoid
regional issues, I guess it is really MUST 711 u-law and a-law on both
ends; otherwise we wind up making it based on location or some darned
thing.  Alternatively, we might think about making u-law and a-law MUST
on the PSAP side only -- premise being if an endpoint does not support
both, its calls using the wrong one for the region will sound like junk
... except for emergency calls.   

On the PSAP end, the MUST list must be longer, to also include any
codecs native to wireless domains the PSAP serves, and real time text
(to avoid Gunnar's wrath ;-).  I do not think it is onerous at all to
make the PSAP end support a long list -- the PSAP end is likely to be an
expensive / sophisticated piece of kit anyway, and very small in number
compared to the zillions able to make calls towards the PSAP.  On
compressed codecs, I believe they SHOULD be supported (BUT NOT
PREFERRED) on PSAP end, as a last resort to avoid failed calls for
misbehaved endpoints that do not agree on 711 or others in the MUST
list.  I believe everything else, such as wb audio, iLBC, video, IM,
etc, becomes SHOULD on the PSAP end.  Perhaps over time, as it becomes
more clear what proportion of endpoints will support the others, the
PSAP MUST list should be extended.   

BTW, Somewhere waaaay down this thread someone said "it's in the BCP".
I don't think it actually is.  I assume it will be added?   

-- Peter 

	"Brian Rosen" <[email-masked]> 

07.08.06 20:20 

        To:        "'James M. Polk'" <[email-masked]>, "'Andrew
Newton'" <[email-masked]> 
        cc:        "'Karihaloo, Ujjval'" <[email-masked]>,
[email-masked] 
        Subject:        RE: [Ecrit] Audio Codecs for 911 CALLS.

I believe that the minimum codec is G.711.  Every PSAP will support it,
every call must be able to support it.

I think we will recommend that every PSAP support the codecs applicable
to
the wireless networks that are in their service boundaries, as well as
wideband codecs that may be supported in their service area, so that
transcoding is not required.  From the emergency service vantage point,
the
lack of standardization in this area (and I do mean "the wonderful thing
about standards is there are so many to choose from") is glaringly,
painfully stupid.

It is unwise to support the compressed codecs (G.723, G.729, ...).  Some
of
the adaptable codecs might be supported in their
better-than-toll-quality
modes.

We might want to recommend support for straight linear 16 bit audio, so
that
transcoding can be minimal loss, although since no transcoders can do
this
now, that might be a futile gesture.

Every PSAP will support the text codec, of course, and I hope, one or
two IM
streams.  Every PSAP will probably (maybe eventually) support H.264, and
some will support H.263.

But in the end, I think these have to be recommendations (SHOULD) and
thus
the MUST, for everyone, is G.711.

AND NO VOICE ACTIVITY DETECTION.

And I don't think this is SPEERMINT territory, even if the subject
matter
overlaps some.  Peering is not assumed to be able to place an emergency
call.

Brian

> -----Original Message-----
> From: James M. Polk [mailto:[email-masked]]
> Sent: Monday, August 07, 2006 6:48 PM
> To: Andrew Newton
> Cc: [email-masked]; Karihaloo, Ujjval
> Subject: Re: [Ecrit] Audio Codecs for 911 CALLS.
> 
> At 06:44 PM 8/7/2006 -0400, Andrew Newton wrote:
> 
> >On Aug 7, 2006, at 6:22 PM, James M. Polk wrote:
> >
> >>At 05:45 PM 8/7/2006 -0400, Andrew Newton wrote:
> >>>
> >>>G.711 is likely not a very good choice for wireless environments.
> >>
> >>
> >>does this mean that my wired IP-phone, like the majority of all
others,
> >>will not have any chance at communicating with anyone else's IP
> >>cellphone?  I think the reverse will have the same problem...
> >
> >That's my non-expert understanding.  Fortunately, we aren't concerned
> with
> >getting a call through between any two UAs: we are concerned about
> getting
> >a call through from any UA to a PSAP.
> 
> err, what do you think will be answering the call in the PSAP?
> 
> (hint: it'll be a UA)
> 
> 
> >-andy
> 
> _______________________________________________
> Ecrit mailing list
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---

From: "Brian Rosen" <[email-masked]>
Date: Tue, 8 Aug 2006 12:02:18 -0400

We’ll need to make a real list if this converges.

________________________________________
From: Stark, Barbara [mailto:[email-masked]] 
Sent: Tuesday, August 08, 2006 11:52 AM
To: [email-masked]; Brian Rosen
Cc: [email-masked]; Karihaloo, Ujjval
Subject: RE: [Ecrit] Audio Codecs for 911 CALLS.

BCP says:

-----Original Message-----
From: [email-masked] [mailto:[email-masked]]
Sent: Tuesday, August 08, 2006 10:34 AM
To: Brian Rosen
Cc: [email-masked]; 'Karihaloo, Ujjval'
Subject: RE: [Ecrit] Audio Codecs for 911 CALLS.

Hi, 

I certainly agree with below, G.711 is a MUST for both ends -- it is the
common denominator supported by virtually everything in one way or another
(one of those possible ways being via transcoding).  To avoid regional
issues, I guess it is really MUST 711 u-law and a-law on both ends;
otherwise we wind up making it based on location or some darned thing.
 Alternatively, we might think about making u-law and a-law MUST on the PSAP
side only -- premise being if an endpoint does not support both, its calls
using the wrong one for the region will sound like junk ... except for
emergency calls.   

On the PSAP end, the MUST list must be longer, to also include any codecs
native to wireless domains the PSAP serves, and real time text (to avoid
Gunnar's wrath ;-).  I do not think it is onerous at all to make the PSAP
end support a long list -- the PSAP end is likely to be an expensive /
sophisticated piece of kit anyway, and very small in number compared to the
zillions able to make calls towards the PSAP.  On compressed codecs, I
believe they SHOULD be supported (BUT NOT PREFERRED) on PSAP end, as a last
resort to avoid failed calls for misbehaved endpoints that do not agree on
711 or others in the MUST list.  I believe everything else, such as wb
audio, iLBC, video, IM, etc, becomes SHOULD on the PSAP end.  Perhaps over
time, as it becomes more clear what proportion of endpoints will support the
others, the PSAP MUST list should be extended.   

BTW, Somewhere waaaay down this thread someone said "it's in the BCP".  I
don't think it actually is.  I assume it will be added?   

-- Peter 

        To:        "'James M. Polk'" <[email-masked]>, "'Andrew Newton'"
<[email-masked]> 
        cc:        "'Karihaloo, Ujjval'" <[email-masked]>,
[email-masked] 
        Subject:        RE: [Ecrit] Audio Codecs for 911 CALLS.

I think we will recommend that every PSAP support the codecs applicable to
the wireless networks that are in their service boundaries, as well as
wideband codecs that may be supported in their service area, so that
transcoding is not required.  From the emergency service vantage point, the
lack of standardization in this area (and I do mean "the wonderful thing
about standards is there are so many to choose from") is glaringly,
painfully stupid.

It is unwise to support the compressed codecs (G.723, G.729, ...).  Some of
the adaptable codecs might be supported in their better-than-toll-quality
modes.

We might want to recommend support for straight linear 16 bit audio, so that
transcoding can be minimal loss, although since no transcoders can do this
now, that might be a futile gesture.

Every PSAP will support the text codec, of course, and I hope, one or two IM
streams.  Every PSAP will probably (maybe eventually) support H.264, and
some will support H.263.

But in the end, I think these have to be recommendations (SHOULD) and thus
the MUST, for everyone, is G.711.

And I don't think this is SPEERMINT territory, even if the subject matter
overlaps some.  Peering is not assumed to be able to place an emergency
call.

Brian

> >>does this mean that my wired IP-phone, like the majority of all others,