Subject: [Sipping] Early Media draft

From: "Ejzak, Richard P (Richard)" <[email-masked]>
Date: Wed, 5 Nov 2003 14:03:53 -0600

Gonzalo,
For completeness, I suggest you incorporate into the early media draft some discussion of early media handling in ITU-T Q.1912.5.  Q.1912.5 uses the presence of encapsulated ISUP in a 180 response to determine that the terminating end is associated with an ISUP endpoint that has in-band call progress information, so that it is not necessary to generate local ringing.  Conversely, the lack of encapsulated ISUP in a 180 response may cause the originating side to generate local ringing.  This effectively provides the functionality I requested in previous correspondence without the need for any SIP extensions.

Richard Ejzak
Lucent Technologies

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From: Gonzalo Camarillo <[email-masked]>
Date: Thu, 06 Nov 2003 09:23:14 +0200

Richard,

this draft is supposed to focus on SIP procedures, not on interworking
with other protocols. RFC 3398 handles interworking with ISUP.

In any case, what you are proposing is an example of a local policy, as 
defined in the draft. So, you are free to implement such a local policy 
(do not generate local ringing tone if an encapsulated ISUP message is 
received) in all the user agents you want.

Thanks,

Gonzalo

Ejzak, Richard P (Richard) wrote:
> Gonzalo, For completeness, I suggest you incorporate into the early
> media draft some discussion of early media handling in ITU-T
> Q.1912.5.  Q.1912.5 uses the presence of encapsulated ISUP in a 180
> response to determine that the terminating end is associated with an
> ISUP endpoint that has in-band call progress information, so that it
> is not necessary to generate local ringing.  Conversely, the lack of
> encapsulated ISUP in a 180 response may cause the originating side to
> generate local ringing.  This effectively provides the functionality
> I requested in previous correspondence without the need for any SIP
> extensions.
> 
> Richard Ejzak Lucent Technologies