Re: [Sip] Invite without offer

["Manpreet Singh" <msingh at ibasis.net>]

usually clients would do this to know the far end full list of capabilities before they send their own offer. although this can be done via OPTIONS, but not everyone supports it and this is the other way of doing it. the media might be delayed but the 200OK is re-transmitted so it should connect fairly quickly. for this reason clients which do this, end up doing 100rel to avoid these kind of situations

 

M

 

 

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From: sip-bounces at ietf.org [mailto:sip-bounces at ietf.org] On Behalf Of Aditya Sehgal
Sent: Tuesday, April 15, 2008 10:50 AM
To: sip at ietf.org
Subject: [Sip] Invite without offer

Hi all,
Is there any practical situation where in an Invite will 
contain no SDP. 
Lets say A calls B. 
My understanding (albeit limited) of 
the RFC makes me believe that 200 OK is sent out when B will pick up the phone. 
Now assuming, the Initial Invite contained no offer (and 100 rel is not 
supported),the first offer is then sent out at 200 OK .If the return ACK is 
either dropped in the IP cloud or is delayed, with no media established, the 
call is essentially useless.

So, is there any situation where it makes 
sense for a UE to send an Invite without an Offer.

Please correct me if 
my assumptions are wrong.

Thanks & Regards,
Aditya Sehgal

-- 
Don't take life too seriously....Nobody comes out alive 
anyway 
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