Caller (A)                     Callee(B)
   |     INVITE                |
   |--------------------------->   |
   |     200 OK                |
   |<----------------------------  |
   |      ACK(dropped)      |
   | ------------x->               |
   |       re-INVITE          |
   | ----------------------------->|                              
   |   200 OK                  |
   |  (retx for 1st Invite)    |
   |<------------------------------|

The scenario is follows

   1. A sends Invite to the  B
   2. B responds with 200 Ok(invite txn terminated)
   3. A sends ACK for 200 Ok which gets dropped on the network ( B is
      retransmitting 200 OK).
   4. Since A has already send ACK A sends re-INVITE.
   5. Meanwhile A receives 200 OK for the 1st INVITE.
   6. Since the there is no txn existing for the the 1st invite, the
      transport sends the response to the UA.
   7. Now the UA behaves as though the 200OK is received for the
      re-invite!!!!!

How to differentiate b/w 200 OK for INVITE or re-INVITE???.
What should be the behavior of the UA for handling of this response.

Pls  Correct if i am wrong....

RFC3261 Snippet:
Note that a UAC MUST NOT initiate a new INVITE transaction within a
dialog while another INVITE transaction is in progress in either direction.
 1. If there is an ongoing INVITE client transaction, the TU MUST
wait until the transaction reaches the completed or terminated state before
initiating the new INVITE.

Regards,
Zabi
 
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