SS7 Diagnostic Indicator to Reason Header IW

The SS7 REL message is very general. The release of a call could be for a number of different reasons. The REL messages on the SIP side such as BYE, and CANCEL try to narrow down the reason a call was released but in some instances does not give enough information. The IMG 2020 has functionality that interworks the diagnostics field information that is embedded in the REL message on the SS7 side and inputs them into the Reason Header's reason-extension field on the SIP side. The feature is enabled or disabled through a field in the SIP_SS7 Interworking object. Refer to the information below. 

SS7 REL Cause Partial Table from ITU Q.850 Specifications Document

Call Flow Diagram

In the call flow diagram below the call is release on the SS7 side with a cause code of User busy and a diagnostic field value of CCBS. With the feature configured, the diagnostic field is mapped and added to the Reason header's Reason Extension field.

Open

Configuration

Below are instructions on how to configure the IMG 2020 to interwork the diagnostic indicator in the reason-header field of the REL messages. Before configuring, the IMG 2020 must have an initial configuration created on it. Refer to the Basic Configurations procedure and verify the basic functionality has been configured. Also, since the feature uses interworking between the SS7 and the SIP protocol, verify the SS7 stacks and channel groups have been configured. Refer to the Configure SS7 topic for more information.

Configure SIP Profile then SIP_SS7 Interworking objects

• Right click on the Profiles object and select New SIP SGP. The SIP Profile with an ID of 0 is a default profile and cannot be modified. Disregard this profile.

• Right click on the Profiles object again and select New SIP SGP. This SIP Profile can now be modified. In the Name field, enter a name that describes the SIP Profile being created. In this procedure the SIP Profile was labeled SIP_Prof_DiagInd_IW. Refer to the SIP Profile - SGP topic for information on configuring the remaining fields.

• Right click on the SIP Profile just created and select New SIP_SS7 Interworking. In the object that appears, select Enable from the drop down menu in the REL Diagnostic field to Reason-extension field. This will enable the feature in the SIP Profile object. Refer to the SIP to SS7 ISUP Interworking topic for information on configuring the remaining fields in this object.

Configure SIP Signaling

• Right click on the IMG Name physical node object and select New Signaling. The Signaling object is a parent or container object and no configuration is needed here. Refer to the Signaling topic for more information on this object.

• Right click on the Signaling object and select New SIP. In the Remote IMG's SIP Profile field, select from the drop down menu the SIP Profile created above. Refer to the SIP Signaling - SIP topic for information on configuring the remaining fields within this object.

Configure the External Remote Gateway

Configure the information needed to communicate with the remote gateway that will be communicating with the IMG using this feature.

• Right click on the IMG EMS object and select New External Network Elements. The External Network Elements object is a parent or container object and no configuration is needed here. Refer to the External Network Elements topic for more information on this object.

• Right click on the External Network Elements object and select New External Gateways. Again, the External Gateways object is a parent or container object and no configuration is needed here. Refer to the External Gateways topic for more information on this object.

  • Right click on the External Gateways object and select New External Gateway.

Configure SS7 Channel Group

• Right click on the Routing Configuration object and select New Channel Groups. The Channel Groups object is a parent or container object and no configuration is needed here. Refer to the Channel Groups topic for more information on this object.

• Right click on the Channel Groups object and select New Channel Group. Enter a name to identify this channel group. In this procedure the name entered was ChGrp_SS7_DiagInd.

• Select SS7 from the drop down menu in the Signaling Type field. Refer to the Channel Group topic for more information on configuring the remaining fields in this object.

• Right click on the Channel Group object and create the ISUP Group. Refer to the ISUP Group topic for more information on configuring this object.

• Right click on the ISUP Group object and select New Circuits. Refer to the SS7 - Circuit Group under Signaling topic for information on configuring the CICs.

Configure SIP Channel Group

• Right click on the Channel Groups object and select New Channel Group. Enter a name to identify this channel group. In this procedure ChGrp_SIP_DiagInd was entered.

• Select SIP from the drop down menu in the Signaling Type field. Refer to the Channel Group topic for more information on configuring the individual fields in this object.

• Right click on the SIP channel group created and select New IP Network Element. Select from the drop down menu of the IP Network Element field the remote gateway configured above. Refer to the IP Network Element topic for more information on configuring the object.

Configure Routing and Translations

At this point, the feature has been configured along with the SIP and SS7 channel groups. The routing and translation configuration can now be achieved so that the calls are between the two channel groups.

Additional Information

• If the feature is enabled and the IMG 2020 receives an SS7 REL message without the diagnostics field embedded, the Reason Extension field will not be populated in the Reason Header.

• Diagnostic information is not available for every cause. In those cases in which the diagnostic is a Q.931 information element, the coding of the diagnostic is the same as for the corresponding information element in clause 4/Q.931.

• When the feature is enabled, the diagnostic field will be included in the outgoing SIP BYE, CANCEL, 4xx, 5xx, and 6xx Reason Header extension field.