Signaling System No.7 Protocol Architecture And Sevices part 69

Appendix E. ITU-T Q.931 Messages The table in this appendix summarizes Q.931 messages and the purpose of each. Q.931 is the layer 3 protocol of the subscriber signaling system used for ISDN and is known as Digital Subscriber Signaling System No. 1 (DSS 1).
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Signaling System No.7 Protocol Architecture And Sevices part 69Appendix E. ITU-T Q.931 MessagesThe table in this appendix summarizes Q.931 messages and the purpose of each.Q.931 is the layer 3 protocol of the subscriber signaling system used for ISDN andis known as Digital Subscriber Signaling System No. 1 (DSS 1). It employs amessage set that is made for interworking with SS7s ISDN User Part (ISUP). Assuch, the message set maps to the ISUP message set. Table E-1. Q.931 MessagesBinary Message PurposeCode Name Call Establishment Messages0000 Alerting0001 Direction: Called User Network and Network Calling User The called user is being alerted; that is, the B partys phone is ringing.0000 Call0010 Proceeding Direction: Called User Network or Network Calling User Call establishment is taking place and, as such, no more call establishment signaling is accepted.0000 Connect0111 Direction: Called User Network and Network Calling User The B party has accepted the call; that is, has answered the phone.0000 Connect1111 Acknowledge Direction: Network Called user or Calling User Network Message sent to indicate that the called user has been awarded the call. If sent to the network by the calling user, the message allows symmetrical call-control procedures.0000 Progress0011 Direction: User Network or Network-> User Sent to indicate the progress of a call in the event of interworking or in relation to the provision of in-band information/patterns (for example, announcements).0000 Setup0101 Direction: Calling user Network and Network Called User Initial message sent to initiate a call.0000 Setup1101 Acknowledge Direction: Called user Network or Network-> Calling User Indicates that call establishment is underway, but additional information might be requested. Call Information Phase Messages0010 Resume0110 Direction: User Network Sent request to resume a previously suspended call.0010 Resume1110 Acknowledge Direction: Network User Indicates to the user that the request to resume a suspended call has been completed.0010 Resume Reject0010 Direction: Network User Indicates to the user that a failure occurred while trying to resume a suspended call.0010 Suspend0101 Direction: User Network Sent to request that a call be suspended.0010 Suspend1101 Acknowledge Direction: Network User Informs the user that a request to suspend a call has been completed.0010 Suspend0001 Reject Direction: Network User Informs the user that a request to suspend a call cannot be completed.0010 User0000 Information Direction: User Network and Network User Sent to transfer information to the remote user. Call Clearing Messages0100 Disconnect0101 Direction: User Network or Network User When sent by the network, indicates that the connection has been cleared end-to-end. When sent from user to network, it is used to request tear down of an end-to- end connection.0100 Release1101 Direction: User Network or Network User Indicates that the channel has been disconnected by the equipment sending the message, and that it intends to release the channel along with the call reference. As a result, the receiving equipment should release the channel and call references after sending a RELEASE COMPLETE.0101 Release1010 Complete Direction: User Network or Network User Sent to indicate that the equipment sending the message has released the channel and the call refere ...