SIP Diversion Header

The IMG 2020 supports the INVITE Diversion Header (Diversion and CC-Diversion) to support PSTN Redirecting Services (also known as Call Forwarding). The INVITE Diversion header carries information about the redirection of a call. The Diversion header prevents this pertinent SS7 redirection information from being lost in the SS7 to SIP conversion. When SS7 redirection information is received on the incoming side, it is relayed in the Diversion header on the outgoing SIP side. To enable or disable SIP Diversion Header see SIP Profile - Headers link.

A charge number parameter is also included in the outgoing IAM message for an SS7 channel group when receiving an INVITE message on an incoming SIP channel group. To eliminate the charge number parameter from getting interworked, refer to the SS7 - Destination - ISUP Group - Parameter Filter topic to disable the passing of the parameter.

For information on how the Diversion Header is displayed in Radius refer to RADIUS - Diversion Info in CDR topic. 

Call Flow Scenarios

SS7 to SIP - Call Forwarding Scenario

Open

SIP to SS7 - Call Forwarding Scenario

Open

ISDN to SIP - Call Forwarding Scenario

SIP to ISDN - Call Forwarding Scenario

SIP to SS7 - Map single Diversion Header into both the Redirecting and Original Called Parameters

In the call flow below, a single SIP Diversion Header is interworked to the SS7 side. In this scenario, the following is true.

• The number in the SIP Diversion Header is interworked to both the Redirecting Number and the Original Called Number.

• If the Original Called Number is not needed on the SS7 side, it can be filtered by setting the Original Called Number field in the SS7 - Destination - ISUP Group - Parameter Filter object to Don't Pass.

• If the Redirecting Number is not needed on the SS7 side, it can be filtered by setting the Redirecting Number field in the SS7 - Destination - ISUP Group - Parameter Filter object to Don't Pass.

SIP to SS7 - NOA Scenario

SS7 to SIP NOA Scenario

The call flow below displays interworking the Nature Of Address parameter from SS7 to SIP. The scenario below is enabled only when the Diversion Header Support is set to either Diversion or CC-Diversion. Refer to SIP Profile - Headers and SIP Profile - Header Parameters. When an SS7 IAM is received, one of the following scenarios will occur.

• If the incoming IAM message contains only the Redirecting Number parameter, the Nature Of Address parameter on the incoming IAM message will be interworked to the outgoing SIP Diversion Header as noa=x.

• If the incoming IAM message contains only the Original Called Number parameter, the Nature Of Address parameter in the incoming IAM message will be interworked to the outgoing bottommost SIP Diversion Header as noa=y.

• If the incoming IAM message contains both the Redirecting Number and Original Called Number, the Nature Of Address parameters will be interworked into two separate Diversion headers. The topmost Diversion Header in the SIP INVITE will contain the Nature Of Address parameter (noa=x) of the Redirecting Number. The bottommost Diversion Header in the SIP INVITE message will contain Nature Of Address parameter (noa=y) of the Original Called number.

Configuration

Initial Configuration

The procedure below explains how to configure the IMG 2020 to interwork the Diversion Header between SS7 and SIP. The configuration of Interworking of Diversion from ISDN to SIP is accomplished similarly. Prior to configuring the feature, a basic configuration along with signaling stacks need to be created. Follow the Basic Configurations procedure to configure the basic functionality and if signaling needs to be configured, information on this can be obtained from one or more of the following:

 Configure SS7

Configure ISDN

Configure SIP (Multiple SIP IP)

Configure SIP (Single SIP IP)

Create a SIP Profile (SGP) and then SIP Headers page

• Right click on the Profiles object and select New SIP Profiles. The SIP Profiles object is a parent or container object. No configuration is needed here. Refer to the SIP Profiles topic for more information on this object.

• Right click on the SIP Profiles object and select New SIP Profile. The first profile that gets created is a Default SIP Profile and cannot be modified. Disregard this profile.

• Right click on the SIP Profiles object and select New SIP Profile again. In the SIP Profile object that appears, either enter a name that identifies this SIP Profile or accept the default name already entered. In this example the SIP Profile was labeled SIP_DiversionHeader_Profile. Refer to the SIP Profile - SGP topic for more information on configuring the remaining fields in this object.

• Right click on the SIP Profile object just created and select New SIP Headers. The Diversion Header Support feature is set to Disabled by default. To enable, select Diversion from drop down menu in the Diversion Header Support field. Refer to SIP Profile - Headers topic for more information on configuring the remaining fields in this object.

Create a Remote Gateway

Create an external network element and link the SIP profile created with the remote SIP gateway. Follow procedure below to communicate with a remote gateway.

• Right click on the Dialogic 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 External Network Elements topic for more information.

• Right click on External Network Elements and select New External Gateways. The External Gateways object is a parent or container object also and no configuration is needed here. Refer to External Gateways for more information.

• Right click on External Gateways and select New External Gateway. Enter a name that identifies the gateway being configured. In this example the gateway was labeled DiversionHeader_GW. Refer to screen capture below.
  
  

Configure SIP Signaling

The configuration above displays how to configure the SIP Profile and External SIP Gateway so that the SIP Diversion Header functionality is configured. The next step is to configure the SIP signaling stack and SIP Channel Groups. Refer to the topic Configure SIP (Single SIP IP) or Configure SIP (Multiple SIP IP) for a procedure on how to configure the SIP functionality.

Diversion Header Mappings

The IMG 2020 implementation of SIP Diversion Header is compatible with RFC 5806.