Customize / Map Cause Codes
By default, if the IMG 2020 receives a cause code on the outgoing leg of a call, the received cause code will be interworked and that same cause code will be transmitted in a response to the incoming side. However, the IMG 2020 has the ability to manipulate the received cause code on the outgoing leg and transmit a modified cause code in the response to the incoming leg. This functionality is supported between any protocol supported on the IMG 2020. The examples below display the configuration needed to modify a received cause code coming from the SS7 protocol modify it and then transmit the modified code to the SIP protocol as a SIP Call Request Failure code.
SIP to SS7
The first example is a call is initiated in the SIP network and is interworked into the SS7 network. The SS7 network rejects the call with a cause code of xxx. The configuration below describes how to map the ISUP cause code to a SIP Call Request Failure code.
It is assumed that the Basic Configurations procedure has been configured and all basic functionality has been set up. The procedure describes the cause code mapping and channel group functionality.
Configure SIP Channel Group (Incoming Leg)
Right click on the Dialogic object and select New Routing Configuration. The Routing Configuration object is a container object and no configuration is needed here. For more information on this object refer to the Routing Configuration topic.
Right click on the Routing Configuration object and select New Channel Groups. The Channel Groups object is a container object for multiple channel groups. No configuration is needed here. For more information refer to the Channel Groups topic.
Right click on the Channel Groups object and select New Channel Group. In the Name field, either except the default name or enter a name that identifies the channel group being configured. In this procedure, the channel group was labeled ChGrp_SIP_Inc.
Select SIP from the drop down menu in the Signaling Type field.
Select the Incoming and Outgoing IP Profile from drop down menu. The IP Profile was initially created in the Create Profiles section above. For more information on configuring the remaining fields in the channel group object, refer to the Channel Group topic.
Refer to the Configure SIP (Single SIP IP) or Configure SIP (Multiple SIP IP) topic for more information on configuring SIP.
Configure SS7 Channel Group (Outgoing Leg)
Right click on the Channel Groups object and select New Channel Group. In the Name field, either except the default name or enter a name that identifies the channel group being configured. In this procedure, the channel group was labeled ChGrp_SS7_out.
Select SS7_ISUP from the drop down menu in the Signaling Type field.
Refer to the Configure SS7 topic for more information on configuring SS7 functions.
Create Cause Code Table and Cause Code Table Element
Right click on the Routing Configuration object and select New Cause Code Tables. No configuration is needed here. The cause code tables object is a container object. Refer to the Cause Code Tables topic for more information on this object.
Right click on the Cause Code Tables object and select New Cause Code Table. Either accept the default name or enter a name in the Name field that describes the Cause Code Table being configured. In this example the cause code table was labeled CCTbl_ConvCauseCode.
Right click on the Cause Code Table and select New Cause Code Table Element. In the Criteria Values field select from the drop down menu the cause code that the IMG 2020 will match on. In this example the cause code 019 No Answer from User was selected.
In the Route Action Type field, select Cause Code from the drop down menu.
In the Outgoing Cause Code field select the Call Request Failure Code that will be sent back to the SIP network. In this example, the Call Request code of 480 - Temporarily Unavailable was selected. Refer to the screen capture below.
Note: The procedure describes how to modify a received cause code received from the SS7 leg and transmit a modified cause code back to the SIP leg. If however the Cause Code received does not need to be modified, there is no need to configure the Cause Code Table. The IMG 2020 will automatically interwork the received cause code from SS7 to the Call Failure Request code in SIP using the default mappings detailed in RFC 3398 and described in the Cause Code Mappings topic in this document.After modifying the Cause Code Table Element, the Cause Code Table object in the configuration tree will have a yellow exclamation point embedded in the icon. This indicates the configuration has not been sent to the IMG 2020 yet. Click on the Cause Code Table object and then click on the Download Routing Table button and the cause code table information will get sent to the IMG 2020. At this point the exclamation point will disappear.
Link Cause Code Table to Incoming SIP Channel Group
After the Cause Code Table has been created and configured, it can be linked to the Incoming channel group. In this procedure the incoming channel group is the SIP channel group. Refer to the screen capture below of the SIP channel group.
Additional Information
If the Cause Code received on the outgoing channel group does not need to be modified, the cause code table and associated Cause Code Table Elements do not need to be configured. The IMG 2020 will automatically interwork the cause code received in the outgoing channel group and transmit the cause code out the incoming channel group.
If the Cause Code received on the outgoing channel group does not need to be modified and the protocols on the incoming and outgoing channel groups are different, the IMG 2020 will automatically interwork the cause code received to whatever protocol is on the incoming channel group.
The incoming leg is SIP and the outgoing leg is SS7. The cause code is received on the outgoing leg is an ISUP cause code. The IMG 2020 is then configured through the Cause Code Table and Cause Code Table Element to modify the ISUP code received to a modified ISUP Cause code. In this case the IMG 2020 will map the modified ISUP cause code to a SIP Call Request Failure code before transmitting it out the incoming SIP leg. Refer to the Cause Code Mappings topic to view a table of standard ISUP Q.931 Cause Code to SIP Request Failure mappings.