IMG 1010 - Redirecting Number Assertion - ISDN to SS7

Redirecting Information may be present in the SS7 IAM messages. It indicates that call forwarding has occurred. This feature allows a user to create and insert individual elements in the Redirection Information and Redirecting Number parameters into an outgoing SS7 IAM message. A new object labeled Redirection Information Assertion is added, and this object is used to insert the Redirection Information and Redirection Number parameters. The feature is supported on a call received from an ISDN network and transmitted to an SS7 network only. Refer to the information below.

Call Flow Diagrams

Set redirection counter to release call

In the example below, the remote SS7 switch is configured to release the call when the Redirection Counter number reaches a value greater than 2.

Example 1

Open

1. The remote SS7 Switch is configured to reject the forwarded call if its Redirection Counter is greater than 2.

2. By using this feature, the user configures the IMG to set the Redirection Counter value to 3.

3. The IMG creates the Redirection Information parameter which contains the configured Redirection Counter parameter and transmits the Redirection Information out to the SS7 network in an SS7 IAM message.

4. The SS7 switch increments and checks the value of the Redirection Counter. Since the Redirection Counter value is set to 3,the remote SS7 switch sends a RELEASE message back to the original caller

5. If the Redirection Counter value was set to less than 2, the SS7 switch would forward the SS7 IAM message. 

Example 2

In the example below, the remote SS7 switch is configured to release the call when the Redirection Counter number reaches a value greater than 2.

Open

1. The remote SS7 Switch on the outgoing SS7 side is configured to reject the forwarded call if its Redirection Counter parameter is greater than 2.

2. By using this feature, the user configures the IMG to insert a value of 2 as the Redirection Counter in the outgoing SS7 IAM message.

3. The IMG creates the Redirection Information parameter containing the configured Redirection Counter parameter.

4. The remote SS7 switch increments and checks the value of the Redirection Counter.

5. Since the Redirection Counter value inserted by IMG is not greater than 3, the remote SS7 switch accepts the call. 

Insert Redirection information into the outgoing IAM message

The call flow below displays the redirection information being inserted.

Configuration

Below are instructions on how to configure the IMG to allow it to add redirection information into the outgoing SS7 IAM message. In the procedure below the incoming side is ISDN and the outgoing side will be SS7 since the feature supports a call going from ISDN to SS7 only.

Verify the following entities are configured before proceeding:

• IMG 1010 - Logical IMG

• IMG 1010 - Physical IMG

• IMG 1010 - Configuring T1 or E1 Bearer Profile - 10.5.x

• IMG 1010 - Configuring T1 or E1 Bearer Spans - 10.5.x

• IMG 1010 - An Overview of SS7 Configuration

 Configure these initial objects before proceeding to the procedure below.

Procedure

Create ISDN Signaling and ISDN Channel Group (Incoming Channel Group)

• Right click on the Signaling object and select New ISDN. A ISDN D-Channels object will get created. This is a container object and no configuration is needed here. Refer to the IMG 1010 - ISDN Signaling Pane topic for more information on this object.

• Right click on the ISDN D-Channels object and select New ISDN D-Channel. Configure the D-Channel in this object. Refer to the IMG 1010 - ISDN D Channel topic for more information on configuring this object.

• Right click on IMG EMS and select New Routing Configuration. A Routing Configuration Pane will appear. Refer to the IMG 1010 - Routing Configuration topic for more information on this object.

• Right click on Routing Configuration and select New Channel Groups. A Channel groups container object is created. This object will allow multiple channel groups to be created beneath it. Refer to the IMG 1010 - Channel Groups topic for more information on this object.

• Right click on the Channel Groups Object and select New Channel Group. A Channel Group Object will appear. Enter a name for this channel group and set the Signaling Type to ISDN. In this example, the channel group was labeled ChGrp_ISDN. Refer to the IMG 1010 - Channel Group topic for more information on configuring this object.

• Right click on the ISDN Channel group just created and select New ISDN Group. Select a D-Channel from drop down menu in the ISDN D channel field. Refer to the IMG 1010 - ISDN Group topic for more information on configuring this object.

• Right click on the ISDN Group object just created and select New ISDN Circuits. Select which spans/channel will be utilized in this ISDN circuits group. Refer to the IMG 1010 - ISDN Circuits topic for more information on configuring this object.

Create SS7 Channel Group (Outgoing Channel Group)

Right click on the Channel Groups Object and select New Channel Group. A Channel Group Object will appear. Enter a name for this channel group and set the Signaling Type to SS7. In this example, the channel group was labeled ChGrp_SS7. Refer to the IMG 1010 - Channel Group topic for more information on configuring this object.

• Right click on the channel group created and select New ISUP Group. Select the correct stack from the OPC-DPC field drop down menu. Refer to the IMG 1010 - ISUP Group topic for more information on configuring this object.

• Right Click on the ISUP group created and select New Circuits. Select the Spans/Channels that will be configured and enter a Starting CIC number. Refer to the IMG 1010 - Circuit Group topic for more information on configuring this object.

Configure the Redirection Information and Redirection Number parameters

Right click on the ISUP group created and select New Redirection Information Assertion. Change the Redirection Information Assertion field to Enabled. Depending on what the user would like to do will depend on which fields are modified. Refer to the topic for more information on configuring the separate fields in this object. See screen capture below.From here, any routing and/or translation tables can be configured. Refer to the routing and translation topics for information on configuring those functions. Refer to the IMG 1010 - Redirection Information Assertion topic for more information on configuring this object

Additional Information

• The Redirection Information Assertion feature is applicable only from ISDN to SS7 and is supported in both ANSI and ITU.

• The Redirection Information Assertion feature is applicable for outgoing SS7 channel groups only.

• When the feature is enabled, the IMG will create the Redirection Information parameter and add it to the SS7 IAM message.

• The digits from the Calling Party Number in the incoming messaging will be used to create the Redirecting Number.

• The IMG will set the values for the advanced parameters in the Redirecting Number parameter with the advanced parameters from the Calling Party Number parameter.

• If the Calling Party Number parameter is not available, the IMG will not create the Redirecting Number parameter but will create the Redirection Information Parameter.

• The IMG will not override the Redirection Information parameter if it is already interworked from the incoming side and is present in the IAM message.

• The IMG will not override the Redirecting Number parameter if it is already interworked from the incoming side and is present in the IAM message.

• If the Channel Group Function field in the SS7 channel group is set for Incoming Trunks, the Redirection Information Assertion object can not be created.

• The feature is applied after both incoming and outgoing translations. The redirecting number which is created from the calling party number will be based on the translated number.

• There will be no compatibility issues regarding mismatched GCEMS and IMG software. If an IMG is running software with the support for this feature and the GCEMS does not, the config bytes would not be present and the option would not be enabled. If the IMG is running software without this feature and the GCEMS has configuration for it, the config bytes would be set but not processed.