Subject: [splices] Using Two Separate Devices to Start a Conversation proposal

From: "Shekh-Yusef, Rifaat (Rifaat)" <[email-masked]>
Date: Thu, 26 May 2011 20:37:00 -0400

Hi,

The following proposal is to cover the first use case in the disaggregated media draft.

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              |                     |                     |
    |-------------------->|                     |                     |
    |                     |                     |                     |
    |                     |                     |                     |

Alice wants to initiate a call to Bob, but wants to use her Desk Phone to receive the audio from Bob and use her PC to send audio to Bob.
The PC instructs the Desk Phone to initiate a call to Bob in a receive only mode.

    |                     |                     |                     |
    | INVOKE Action: urn:invoke:call:initiate;media=audio;direction=recvonly;target=bob@whatever
    |-------------------->|                     |                     |
    | OK                  |                     |                     |
    |<--------------------|                     |                     |
    |                     | INVITE [recvonly]   |                     |
    |                     |-------------------->|                     |
    |                     |                     | INVITE [recvonly]   |
    |                     |                     |-------------------->|
    |                     |                     | 180                 |
    |                     | 180                 |<--------------------|
    |                     |<--------------------|                     |
    |                     |                     | 200 OK              |
    |                     | 200 OK              |<--------------------|
    |                     |<--------------------|                     |
    |                     |                     |                     |
As soon as Bob answers the call, a NOTIFY is sent to Alice's PC (dialog event package)
    |                     |                     |                     |
    | NOTIFY              |                     |                     |
    |<--------------------|                     |                     |
    | OK                  |                     |                     |
    |-------------------->|                     |                     |
    |                     |                     |                     |
PC sends a new INVITE with Join with a sendonly SDP offer
    |                     |                     |                     |
    | INVITE Join [sendonly]                    |                     |
    |-------------------->|                     |                     |
    | 100 Trying          |                     |                     |
    |<--------------------|                     |                     |
    |                     |                     |                     |
    |                     | re-INVITE [sendrecv]|                     |
    |                     |-------------------->|                     |
    |                     |                     | re-INVITE [sendrecv]|
    |                     |                     |-------------------->|
    |                     |                     | 200 OK              |
    |                     | 200 OK              |<--------------------|
    |                     |<--------------------|                     |
    | 200 OK              |                     |                     |
    |<--------------------|                     |                     |
    |                     |                     |                     |
    |                     |                     |                     |
    |<----dialog2-------->|<---dialog1------------------------------->|
    |                     |                     |                     |
    |                     |<======audio===============================|
    |=============================audio==============================>|
    |                     |                     |                     |
    |                     |                     |                     |