Transaction ID
The transaction ID is a TCAP reference for a set of TCAP operations that are performed within a single dialog. When machine A starts a TCAP dialog with another machine B, the machine A sends a Begin message to machine B. This Begin message contains an Originating Transaction ID, which is the Transaction ID reference for A. When the machine B replies to A with a Continue message it includes A's Transaction ID as the Destination Transaction ID. Furthermore B includes its own Transaction ID as the Originating Transaction ID.
As the TCAP dialog goes on each Continue message includes the Transaction ID of the destination machine as the Destination Transaction ID and the Transaction ID of the originating machine as the Originating Transaction ID. When any of the machines wants to close the dialog it sends an End message or an Abort message to the other machine. This message contains the Destination Transaction ID only.
Read more about this topic: Transaction Capabilities Application Part