processing mid - dialog sip messages by receiving a mid - dialog sip message from a sip user agent client , creating a new sip session , associating the new sip session with the mid - dialog sip message , identifying an application that is associated with the mid - dialog sip message , providing to the application the mid - dialog sip message in the context of the new sip session , receiving an acknowledgement from the application that the application will accept the mid - dialog sip message , and responsive to receiving the acknowledgement , providing to the application the mid - dialog sip message in the context of the new sip session .