A                 KA                      B
        INVITE                   ->
        200 OK(INVITE)    <-
        ACK is lost
        BYE                       <-
        200 OK(BYE)         ->
        200 OK(INVITE)    <-
        200 OK(INVITE)    <-
        200 OK(INVITE)    <-


ACK is lost AND A sent BYE cmd,B do not recv ACK and is also Retransmission 200 OK, How can I distinguish this 200 OK and drop it?

thaks