Re: [splices] Answering a Call Using Two Separate Devices proposal

[Paul Kyzivat <[e-mail]>]

inline

On 4/27/2011 11:49 AM, Shekh-Yusef, Rifaat (Rifaat) wrote:
>
>> -----Original Message-----
>> From: [e-mail] [mailto:[e-mail]] On Behalf Of
>> Paul Kyzivat
>> Sent: Monday, April 25, 2011 8:44 AM
>> To: [e-mail]
>> Subject: Re: [splices] Answering a Call Using Two Separate Devices proposal
>>
>>
>> On 4/25/2011 12:26 AM, [e-mail] wrote:
>>>
>>>
>>> Then, during the adding video stream stage, Alice's desk phone send
>>> INVITE(with video) to Alice's PC. I think Alice PC can accept the INVITE
>>> request by Alice's manual action, while not by the refer-action indication.
>>
>> Yes, that is certainly possible.
>> What is tricky is what appears on the UI of the PC in this circumstance.
>> Some possibilities:
>> - appears as a "normal" (new) video call from Alice
>> - appears as a "normal" (new) video call from Bob
>> - appears as something special - a request for video support
>>    from the desk phone.
>>
>> To get this to be anything but the first of the above will require
>> *something* we don't currently have.
>>

> I think that we should try to achieve the second option of the 3 options you listed above.

Well, the 2nd is "better" than the first, but the third is better than 
the second. So if it can be achieved, all the better.

> How about if the PC subscribes to the Desk Phone dialog event package with include-session-description, combined with Peter's idea of slow start INVITE with Join from the PC, as follows:
>
>      | SUBSCRIBE Event: dialog;include-session-description             |
>      |-------------------->|                     |                     |
>      | 200                 |                     |                     |
>      |<--------------------|                     |                     |
>      | NOTIFY [100 Trying] |                     |                     |
>      |<--------------------|                     |                     |
>      | OK                  |                     |                     |
>      |-------------------->|                     |                     |
>
> (*)
>      |                     |                     |                     |
>      |                     |                     |                     |
>      |                     |                     |                     |
> The following is a re-INVITE from the remote party (Bob) to add video
> to the existing audio call
>      |                     |                     |                     |
>      |                     |                     | INVITE Alice [A/V]  |
>      |                     |                     |<--------------------|
>      |                     | INVITE Alice [A/V]  |                     |
>      |                     |<--------------------|                     |
>      |                     | 100 Trying          |                     |
>      |                     |-------------------->|                     |
>      |                     |                     | 100 Trying          |
>      |                     |                     |-------------------->|
>      |                     |                     |                     |
>      |                     |                     |                     |
> The PC gets a notification of the new incoming call and the fact that it
> is video call.
>      | NOTIFY dialog-info with session description                     |
>      |<--------------------|                     |                     |
>      | 200 OK              |                     |                     |
>      |-------------------->|                     |                     |
>      |                     |                     |                     |
> The PC prompts the user and waits for his response. When the user
> accepts the request, the PC initiates a slow start INVITE to the Desk
> Phone as follows:
>      |                     |                     |                     |
>      | INVITE Join dialog1 |                     |                     |
>      |-------------------->|                     |                     |
>      | 200 [Video]         |                     |                     |
>      |<--------------------|                     |                     |
>      | ACK [Video]         |                     |                     |
>      |-------------------->|                     |                     |

Its a leap of faith here to assume that the phone will realize what it 
is expected to do when there is no offer in the invite.

Clearly it has to offer *something*. So *maybe* when the invite has Join 
it will know it should offer something related to the current call. But 
at the least it has the option of offering either just video, or audio 
plus video. And in some sense it is a policy decision which it should do.

I think we need to find a way to eliminate the leaps of faith, and 
replace with some plausible procedures coupled with some reasonable 
policy knobs.

	Thanks,
	Paul

>      |                     | 200 OK [A/V]        |                     |
>      |                     |-------------------->|                     |
>      |                     |                     | 200 OK [A/V]        |
>      |                     |                     |-------------------->|
>      |                     |                     |                     |
>
>
> Regards,
>   Rifaat
>
>
>