Subject: RE: [Sipping] New draft on session mobility

From: Ali Irfan-FIA225 <[email-masked]>
Date: Tue, 15 Mar 2005 09:39:28 -0600

Hi,

Very nice and informative draft. Thank you. 

I have a question about how to enable the following session-mobility scenario, not explicitly covered in your draft (but would like your comments). User A and B, both are connected via the IP and also at each end have POTS connection (the IP device can setup call on the POTS-phone). User-A and User-B have a audio media-session going through their IP-devices. In the middle of the call, User-A would like to move the audio-session over to the POTS side. Still later in the call, User-A will again move the call back to the IP-side.

One approach for User-A to make the first switch could be to send a re-INVITE to User-B containing SDP using the PINT (RFC 2848) extension:

	c= TN RFC2543 +1-201-000-0000
	m= audio 1 voice

User-B can respond with its phone number SDP part of the 200 OK, if it agrees to support the call

	c= TN RFC +1-201-000-0001
	m= audio 1 voice

Then User-A can go ahead and setup the call on the PSTN side. 

Later when User-A wants to retrieve the session, it can send another re-INVITE to User-B, with now the SDP parameters for IP-session to be established. User-A can then hang-up the POTS line.

Wondering if this is a valid approach, and/or there is another preferred approach.

Thanks
Irfan

> [mailto:[email-masked]] On Behalf Of Henning Schulzrinne
> We've written a new draft on options for providing 
> mid-session mobility:
> 
http://www.ietf.org/internet-drafts/draft-shacham-sipping-session-mobility-00.txt

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