TCAP:Message

A TCAP message consists of three portions: the transaction portion (which contains the message type and parameters), the dialogue portion (which contains the application context name), and the component portion.

Transaction portion

These types of messages can be received or transmitted by the transaction portion of TCAP across the SCCP transport service:

ITU, ETSI

• Unidirectional
• Begin
• Continue
• End
• Abort

ANSI

• Unidirectional
• Query with permission
• Query without permission
• Conversation with permission
• Conversation without permission
• Response
• Abort

All TCAP messages except unidirectional message are implied for structured dialogue. Unidirectional message is implied for unstructured dialogue.

Dialogue portion

The dialogue portion is optional in a TCAP message and can only be present in 1992, 1996 ITU TCAP, 1996 ETSI TCAP, and 1996 ANSI TCAP messages. The dialogue portion is used to exchange the application context name and user-specific information.

Component portion

The component portion is mandatory in 1988 ITU TCAP, and 1988, 1992 ANSI TCAP messages, and is optional in other supported versions of TCAP. The following protocol data units (PDUs) can be received or transmitted in the component portion of a TCAP message:

ITU, ETSI

• Invoke
• Return result not last
• Return result last
• Return error
• Reject

ANSI

• Invoke not last
• Invoke last
• Return result not last
• Return result last
• Return error
• Reject