Cause Code Conversions

Owned by Kelli Higdon
Last updated: Apr 02, 2024
5 min read

 

The IMG 2020 supports converting or modifying a received cause code from the ISDN, SS7, SIP, or H.323 protocol. When the functionality is configured, the IMG 2020 can receive either an ISUP Q.931 supported cause code or RFC 3398 supported SIP Release Code, and convert it to a modified or converted cause or release code. The Configuration procedure below describes the configuration needed to accomplish the following example:

 Example:

In the configuration example below, the IMG 2020 will receive a call on a SIP channel group on the incoming side. The call is then transmitted out an SS7 channel group to a remote ISUP entity. The remote ISUP entity rejects the call and transmits a 003 cause code (No Route To Destination) back to the IMG 2020. Upon receipt of the 003 cause code, the IMG 2020 converts the received 003 cause code to a 029 cause code (Facility Rejected). Once converted, the call is then interworked through the IMG 2020 back to the SIP side. Since the call is going from the ISUP channel group back to SIP channel group, the cause code is mapped to a SIP Release code of 510 (Not Implemented) and transmitted back to the remote SIP entity. Refer to the Cause Code Mappings topic for a table displaying the mappings between the SIP and ISUP protocols.

 This example displays a SIP to ISUP scenario. However, the IMG 2020 supports the above functionality between any of the supported protocols. Note that on a SIP to SIP scenario, the IMG 2020 will initially convert the received Release Code to a modified release code. After the conversion, the modified release code is interworked through the IMG 2020. The Release code interworked and transmitted out the incoming side will be the converted release code since there are no mappings happening when the incoming and outgoing protocols are both SIP.

 

If the Release Reason received from the remote SIP side contains a Q.850 Reason Header, the release reason in the Reason Header takes priority over any Release codes received. Refer to the topic for more information on this.

Configuration

The procedure below describes how to configure the Cause Code Conversion functionality only. It is assumed that all the basic configurations in the IMG 2020 have been attained. Refer to the topic for information on how to configure the basic functionality such as DS-1s, IP Bearer ports, network interfaces, etc. Also, since the call is being made between SS7 and SIP, the SS7 and SIP stacks must be configured. Refer to the Configure SS7, Configure SIP (Single SIP IP), and Configure SIP (Multiple SIP IP) topics for information on how to achieve this.

Configure Incoming SIP Channel Group and Outgoing SS7 channel groups

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

  • Right click on the Routing Configuration object and select New Channel Groups. The Channel Groups object is a container object as well 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 that identifies this channel group. In this procedure the channel group was labeled ChGrp_SIP_ConvCauseCode.

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

  • Right click on the Channel Groups object and select New Channel Group. Enter a name that identifies this channel group. In this procedure the channel group was labeled ChGrp_SS7_ConvCauseCode.

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

  • Under the SS7 Channel group object, create the Circuit Group object. Refer to the ISDN Circuit Group under Channel Group topic for information on configuring the CIC group.

  • Once the channel groups have been configured, the Channel Groups icon will have a yellow exclamation point embedded in it. This indicates that the configuration needs to be sent to the IMG 2020. Click on the Channel Groups icon with the exclamation point and then click on the Download Resource Tables button. At this point the channel group configuration will get sent to the IMG 2020 node and the yellow exclamation point will disappear. 

Configure Cause Code Table to make to Convert the cause codes.

  • Right click on the Routing Configuration object and select New Cause Code Tables. The cause code tables object is a container object and no configuration is needed here. Refer to the Cause Code Tables topic for more information.

  • Right click on the Cause Code Tables object and select New Cause Code Table. Refer to the screen capture below.

For more information on configuring the individual fields, refer to the Cause Code Table topic.

  • Right Click on the Cause Code Table object and select New Cause Code Table Element. The cause code table element will get created. Refer to the information below.

Field Descriptions

  • Route Criteria Type - The Route Criteria field will default to Cause Code and cannot be modified.

  • Criteria Values - This is the cause code that will be matched on from the side that is rejecting the call. Select from drop down menu what cause code to match on.

  • Route Action Type - This field displays the action to take when the Route Criteria field is matched on. For this procedure Cause Code was selected from the drop down list.

  • Outgoing Cause Code - This is what the matched on cause code will be converted to and then interworked through the IMG 2020. In this procedure, Facility Rejected was selected from the drop down list.

Refer to the Cause Code Table Element topic for more information on configuring the remaining individual fields.

  • Add any other Cause code entries as required.

  • The Cause Code Table will now have a yellow exclamation point embedded in its icon. This indicates the configuration needs to be sent to the IMG 2020 node. Click on the Cause Code Table object in the configuration tree. Click on the Download Routing Table button and the configuration will get sent to the IMG 2020 and the yellow exclamation point will disappear.

  • The Cause Code Table and Cause Code Entries can now be linked to the outgoing SS7 channel group. Click on the SS7 channel group created earlier. Select the Cause Code Table from the drop down menu of the Cause Code Table field. Refer to the screen capture below.

Refer to the Channel Group topic for more information on this object.

  • The cause code conversion functionality has been configured, routing between the two channel groups can now be configured.
     

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