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

Salvatore Loreto <salvatore.loreto@ericsson.com> Mon, 02 May 2011 14:13 UTC

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Date: Mon, 02 May 2011 16:13:41 +0200
From: Salvatore Loreto <salvatore.loreto@ericsson.com>
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Subject: Re: [splices] Answering a Call Using Two Separate Devices proposal
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I think it is a good step forward,

the only comment I have
it is that in order to call it a "loosely coupled" scenario we have 
still to define what happens
if "Alice Desk phone" can not remain in the session for the entire 
session duration...

as the charter defines:

   The objective of this working group is to develop a framework for
   disaggregated media in "loosely-coupled" scenarios, where no single
   device needs to remain in the session for its entire duration and no
   single device needs to act as a master.


/Sal

On 5/2/11 3:45 PM, Peter Musgrave wrote:
> Hi Rifaat,
>
> I think this works well. Thanks for re-stating this clearly.
>
> I see a couple of next steps here:
> - how is in incoming call which has an initial A+V answered?
> - how is an outgoing call which has an initial A+V audio created?
> - if both ends are "loosely coupled" are there any optimizations or shortcuts that seem worthwhile?
>
> I don't think there is anything too tricky about these - but they will need to be worked through. I agree with Simon that it seems time to start to capture this work in a draft.
>
> Regards,
>
> Peter Musgrave
>
> On 2011-05-01, at 11:41 AM, Shekh-Yusef, Rifaat (Rifaat) wrote:
>
>> Hi,
>>
>> In the following flow, I have tried to incorporate all the feedback that I received so far.
>> The only open issue that I am aware of is the issue of what to present to the user on the PC when the phone initiates a video call to the PC (see (#) below).
>>
>> Can you please review the flow below and let me know if we have any other open issues?
>>
>> Regards,
>> Rifaat
>>
>>
>>
>>    Alice                 Alice                Proxy                  Bob
>>     PC                 Desk Phone
>>     |                     |                     |                     |
>>     |                     |                     |                     |
>> Both Alice's devices subscribe to the reg event package, which allows each device to
>> discover the capabilities of the other device based on the feature tags provided by each device.
>> The Desk Phone knows that the PC supports Video, while the PC knows that the Desk Phone only supports audio.
>>     |                     |                     |                     |
>>     |                     | SUBSCRIBE reg       |                     |
>>     |                     |-------------------->|                     |
>>     |                     | 200 OK              |                     |
>>     |                     |<--------------------|                     |
>>     |                     |                     |                     |
>>     | SUBSCRIBE reg       |                     |                     |
>>     |------------------------------------------>|                     |
>>     | 200 OK              |                     |                     |
>>     |<------------------------------------------|                     |
>>     |                     |                     |                     |
>>     |                     |                     |                     |
>> The two devices also subscribe to the dialog of each other.
>>     |                     |                     |                     |
>>     |                     |                     |                     |
>>     | SUBSCRIBE dialog    |                     |                     |
>>     |-------------------->|                     |                     |
>>     | 200 OK              |                     |                     |
>>     |<--------------------|                     |                     |
>>     |                     |                     |                     |
>>     | SUBSCRIBE dialog    |                     |                     |
>>     |<--------------------|                     |                     |
>>     | 200 OK              |                     |                     |
>>     |-------------------->|                     |                     |
>>     |                     |                     |                     |
>>     |                     |                     |                     |
>> The scenario starts with an audio call from Bob to Alice
>>     |                     |                     |                     |
>>     |                     |                     | INVITE Alice [Audio]|
>>     |                     |                     |<--------------------|
>>     |                     | INVITE Alice [Audio]|                     |
>>     |                     |<--------------------|                     |
>>     | INVITE Alice [Audio]|                     |                     |
>>     |<------------------------------------------|                     |
>>     |                     |                     |                     |
>> Let's assume that Alice used her PC to instruct the phone to answer the call
>>     |                     |                     |                     |
>>     | REFER Refer-To: urn:sip-action:call:answer;transducer=speaker|headset
>>     |-------------------->|                     |                     |
>>     | 200 OK              |                     |                     |
>>     |<--------------------|                     |                     |
>>     |                     |                     |                     |
>>     |                     | 200 OK [Audio]      |                     |
>>     |                     |-------------------->|                     |
>>     |                     |                     | 200 OK [Audio]      |
>>     |                     |                     |-------------------->|
>>     | CANCEL              |                     |                     |
>>     |<------------------------------------------|                     |
>>     |                     |                     |                     |
>>     |                     |<---dialog1------------------------------->|
>>     |                     |                     |                     |
>>     |                     |<======audio==============================>|
>>     |                     |                     |                     |
>>     |                     |                     |                     |
>>
>> (*)
>>
>>     |                     |                     |                     |
>>     |                     |                     |                     |
>>     |                     |                     |                     |
>> The following is a re-INVITE from the remote party (Bob) to add video to the existing audio call
>>     |                     |                     |                     |
>>     |                     |                     | reINVITE Alice [A/V]|
>>     |                     |                     |<--------------------|
>>     |                     | reINVITE Alice [A/V]|                     |
>>     |                     |<--------------------|                     |
>>     |                     | 100 Trying          |                     |
>>     |                     |-------------------->|                     |
>>     |                     |                     | 100 Trying          |
>>     |                     |                     |-------------------->|
>>     |                     |                     |                     |
>> The Desk Phone cannot handle video, but it knows that the PC can handle video,
>> so the Desk Phone initiates a new video INVITE to the PC.
>> Alert-Info is used to control the alerting level.
>>     |                     |                     |                     |
>>     |                     |                     |                     |
>> (#) | INVITE [Video]      |                     |                     |
>>     |        Alert-Info: whatever               |                     |
>>     |<--------------------|                     |                     |
>>     | 180                 |                     |                     |
>>     |-------------------->|                     |                     |
>>     |                     |                     |                     |
>> The user can answer the video call using his PC, which would result on
>> 200 OK with video answer being sent to the phone.
>> If the user chose to answer the incoming video call using his Desk Phone,
>> the following REFER will be sent to the PC, before the 200 OK with the
>> video answer is sent from the PC.
>>     |                     |                     |                     |
>>     | REFER Refer-To: urn:sip-action:call:answer                      |
>>     |<--------------------|                     |                     |
>>     | 200 OK              |                     |                     |
>>     |-------------------->|                     |                     |
>>     |                     |                     |                     |
>>     | 200 OK [Video]      |                     |                     |
>>     |-------------------->|                     |                     |
>>     |                     |                     |                     |
>>     |                     | 200 OK [A/V]        |                     |
>>     |                     |-------------------->|                     |
>>     |                     |                     | 200 OK [A/V]        |
>>     |                     |                     |-------------------->|
>>     |                     |                     |                     |
>>     |<----dialog2-------->|<---dialog1------------------------------->|
>>     |                     |                     |                     |
>>     |                     |<======audio==============================>|
>>     |<============================video==============================>|
>>     |                     |                     |                     |
>>     |                     |                     |                     |
>>
>>
>>
>> Now let's assume that Alice is the side that wants to add video to the
>> existing audio call. The scenario continues after the (*) above.
>>
>> Alice can use her phone to add video to the existing audio call. The phone
>> must present a UI to Alice to allow her to do just that. If Alice chooses
>> to use her phone, the following REFER will be sent from the phone to the PC,
>> which will instruct the PC to immediately send an INVITE with video offer
>>
>>     | REFER Refer-To: urn:sip-action:call:join;dialog=dialog1;media=video
>>     |<--------------------|                     |                     |
>>     | 200 OK              |                     |                     |
>>     |-------------------->|                     |                     |
>>     |                     |                     |                     |
>>
>> Alice can use her PC to add video to the existing audio call.
>> The PC knows that there is an existing dialog between the Desk Phone
>> and Bob and present this to Alice for her to choose if she wants to
>> add video to the existing audio call or not. In this case Alice chose
>> to add video to the existing audio call, so the PC sends the following
>> request:
>>     |                     |                     |                     |
>>     |                     |                     |                     |
>>     | INVITE with Join [Video]                  |                     |
>>     |-------------------->|                     |                     |
>>     | 100                 |                     |                     |
>>     |<--------------------|                     |                     |
>>     |                     | re-INVITE [A/V]     |                     |
>>     |                     |-------------------->|                     |
>>     |                     |                     | re-INVITE [A/V]     |
>>     |                     |                     |-------------------->|
>>     |                     |                     | 200 OK [A/V]        |
>>     |                     | 200 OK [A/V]        |<--------------------|
>>     |                     |<--------------------|                     |
>>     | 200 OK [Video]      |                     |                     |
>>     |<--------------------|                     |                     |
>>     |                     |                     |                     |
>>     |                     |                     |                     |
>>     |<----dialog2-------->|<---dialog1------------------------------->|
>>     |                     |                     |                     |
>>     |                     |<======audio==============================>|
>>     |<============================video==============================>|
>>     |                     |                     |                     |
>>     |                     |                     |                     |
>>     |                     |                     |                     |
>>
>>
>>
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