Terms/Abbreviations
CIC: Circuit Identification Code
OPC: Origination Point Code
DPC: Destination Point Code
SLS: Signalling Link Selection
COT (Continuity Test): To test continuity of bearer channel
ISUP Messages
Complete list of ISUP messages and descriptions:
http://www.asknumbers.com/SS7ISUPMessages.aspx
ACM (Address Complete Message)
An Address Complete Message (ACM) is sent in the "backward" direction to indicate that the remote end of a trunk circuit has been reserved.
The originating switch responds to an ACM message by connecting the calling party's line to the trunk to complete the voice circuit from the calling party to the called party. The terminating switch sends a ringing tone to the calling party's line.
ANM (Answer Message)
When the called party answers, the destination switch terminates power ringing of the called line, removes audible ringing tone from the calling line and sends an Answer Message (ANM) to the originating switch. The originating switch initiates billing after verifying that the calling party's line is connected to the reserved trunk.
Call Progress Message (CPG)
CPG is sent in either direction during the set-up or active phase of the call, indicating that an event, which is of significance, and should be relayed to the originating or terminating access, has occurred.
Circuit Group Response Message (CQR)
Sent in response to a Circuit/CIC Group Query message to indicate the state of all circuits/CICs in a particular range.
Circuit Group Reset Acknowledgement Message (GRA)
GRA is sent in response to a Circuit/CIC Group Reset message indicating that the requested group of circuits/CICs has been reset. The message also indicates the maintenance blocking state of each circuit/CIC.
Confusion Message (CFN)
CFN is sent in response to any message (other than a confusion message) if the node does not recognize the message or detects a part of the message as being unrecognized.
Connect Message (CON)
CON is sent in the backward direction indicating that all the address signals required for routeing the call to the called party have been received and that the call has been answered.
Continuity Message (COT)
COT is sent in the forward direction indicating whether or not there is continuity on the preceding circuit(s) as well as of the selected circuit to the following exchange, including verification of the communication path across the exchange with the specified degree of reliability.
Facility Reject Message (FRJ)
FRJ is sent in response to a facility request message to indicate that the facility request has been rejected.
Information Message (INF)
INF is sent to convey information in association with a call, which may have been requested in an information request message.
Information Request Message (INR)
INF is sent by a node to request information in association with a call.
