N2 DSG-SCP

Overview

The DSG-SCP Application is responsible for handling CAMEL/INAP call-session control under the direction of a Diameter-capable Online Charging Server (OCS). Communication with the OCS is via an N2SVCD DiameterApp which manages the Diameter transport layer. Communication with the CAMEL Mobile Switching Centre (MSC) or INAP Service Switching Point (SSP) is via an N2SVCD SigtranApp which manages the TCAP/SIGTRAN transport layer.

Interaction may also include announcements with the support of an INAP-capable Specialized Resource Platform (SRP) either on-switch using the INAP/CAMEL ConnectToResource (CTR) operation or external using the INAP/CAMEL EstablishTemporaryResource (ETC) operation.

N2SVCD Components

When deploying the N2DSG-SCP product, the DsgScpApp (Diameter/CAMEL Gateway) application is used in conjunction with other components as shown in the following component deployment diagram:

Note that the DSG-SCP will typically use a an on-switch or external Specialized Resource Platform (SRP) to perform audio announcements and/or to collect DTMF input.

All interaction between the N2SCP and the SRP components is performed via the SigtranApp over an SCTP/SIGTRAN link.

See also the general product page for the N2 DSG-SCP.

Traffic Type Determination

Received calls may be for Originating, Forwarding, or Terminating call legs. Some factors of processing (e.g. Diameter Result-Codes) may be required to take the traffic type into account.

The DSG-SCP applies the following rules, in order, to determine the traffic type of a received InitialDP:

  1. If the InitialDPEventTypeBCSM field value is 12 (termAttemptAuthorized), set the traffic type to Terminating.

  2. If:

    1. The SSP model inap value is camel1, camel2, camel3, or camel4.
    2. The InitialDPEventTypeBCSM field value is 2 (CollectedInfo) or 3 (AnalyzedInformation).
    3. The InitialDPlocationInformation field is present.

    …set the traffic type to Forwarding.

  3. If:

    1. The SSP model inap value is cs1.
    2. The InitialDPEventTypeBCSM field value is 2 (CollectedInfo) or 3 (AnalyzedInformation).
    3. The InitialDPredirectingPartyID field is present.

    …set the traffic type to Forwarding.

  4. If the InitialDPEventTypeBCSM field value is 2 (CollectedInfo) or 3 (AnalyzedInformation), set the traffic type to Originating.

The call type may be used within selector rules as required.

Subscriber Selection

For each traffic type, the value of the subscriber MSISDN for insertion into the Diameter Subscription-IdSubscription-Id-Data and/or Subscription-Id-Extension AVPs is set from the InitialDP as follows:

Refer to the DSG-SCP configuration for further details.