Subject: [SIP] SIP and SIP-T distinction.

From: "Andy Duncan" <[email-masked]>
Date: Thu, 26 Oct 2000 14:45:00 +0100

Hi,

I realise that SIP-T is not a new protocol specification but simply details
the methods, standards and tools necessary to enable MGC's to inter operate
via the SIP protocol BUT is there an easy way to distinguish bewteen SIP and
SIP-T messages (i.e. messages with encapsulated ISUP as well as SDP).

For example, will a SIP-T message have its own SIP-VERSION to go in the
request/response header - SIP-T/1.0 ?

Or is the message body is defined as having CONTENT-TYPE of multipart/mixed
can you assume it is a SIP-T message ?  I take it this too much to assume as
there is no doubt other expansions of SIP that use this MIME format for
multiple payloads, or is likely to be so in the future. Also, is it likely
that multipart/mixed may just be used to carry the SDP information on its
own instead of application/sdp ?

Or is the only way to determine whether there is an ISUP payload is to delve
into the message body and look for CONTENT-TYPE application/isup ?

Finally, is it also tto much to assume that the SDP payload will always
precede the ISUP payload in the message body ?

Hopefully, I have not polluted your mailing list with my inane ramblings,
but I have scoured your FAQ section and archives to no avail !!

Thanks for any help anyone is prepared to give.

Andy.
============================
Andrew S Duncan
Agilent Technologies
Tel: 0131 331 7822   Exten: 32822
Mailstop: SQFR&D3
============================

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---

From: Jonathan Rosenberg <[email-masked]>
Date: Fri, 27 Oct 2000 18:30:52 -0400

> -----Original Message-----
> From: David Shrader [mailto:[email-masked]]
> Sent: Thursday, October 26, 2000 10:54 PM
> To: [email-masked]; [email-masked];
> [email-masked]
> Subject: Re: [SIP] SIP and SIP-T distinction.
> 
> 
> I don't think we should be treating SIP-T as a separate 
> protocol. There just
> happen to be additional components to the message and you 
> either understand
> them or you don't. If you don't understand something and you 
> don't need to
> understand, then ignore it. If you do need to understand it, 
> then reject it.

And make sure that, in the case of a body you don't understand, this
rejection contains an Accept header listing allowed bodies, so that the UAC
(a softswitch in this case), can resubmit the request without the additional
data.

It is critical that basic call establishment between any basic SIP entities
be possible.

-Jonathan R.
---
Jonathan D. Rosenberg                       72 Eagle Rock Ave.
Chief Scientist                             First Floor
dynamicsoft                                 East Hanover, NJ 07936
[email-masked]                     FAX:   (973) 952-5050
http://www.cs.columbia.edu/~jdrosen         PHONE: (973) 952-5000
http://www.dynamicsoft.com