The IM-SSF module provides support for protocol translation from SIP to ETSI INAP CS1 and CAP v1/v2/v3.

Support for translation into other SS7 protocols are part of the IM-SSF module roadmap.

The IM-SSF module implements most of the features of the IMS specification (3gpp 23.278 'IM CN Interworking'), plus some additional features (such as support for ETSI INAP CS1).

Standalone IM-SSF

The IM-SSF is also available as a dedicated standalone product. Contact your OpenCloud sales representative for more details.

Below are tables outlining features related to 3gpp 23.278, plus additional features of the IM-SSF.

Feature supported Description

CAPv1, CAPv2, CAPv3

supports CAMEL phase 1, 2, and 3

Call Control

supports messages such as InitialDP, RequestReportBCSM, EventReport, Connect, Continue


supports FurnishChargingInformation, ApplyCharging, and ApplyChargingReport

User Interaction

supports ConnectToResource and PlayAnnouncement, acting as an assisting SSF when it receives and EstablishTemporaryConnection, and responding with a second dialog starting with an AssistRequestInstructions


supports both originating and terminating subscription information

Feature NOT supported Description

CAP v4

does not yet support CAMEL phase 4


does not yet support dialed subscription information


does not yet include a method for translating PromptAndCollect

Additional features

Feature supported Description


The IM-SSF provides the same set of features for various INAP variants as it does for CAMEL. INAP variants currently supported are: ETSI INAP CS1, Ericsson INAP CS1 (optional), and Ericsson INAP CS1+ (optional).

Tip A version of IM-SSF that supports other proprietary vendor variants of INAP is available on request. Please contact your OpenCloud sales representative for more information.

Multiple media servers

The IM-SSF uses lookup tables (which can support many entries) to map the parameters received from the SCP to the address of the media server to use. Can also provision a default media server.

Configurable routing to the media server

Some operators prefer the IM-SSF to route directly to the media server; others prefer the route to go back through the S-CSCF. Routing method is configurable per media server. Can also define default routing behaviour.


Can enable detail tracing per CSI using an additional field in the CSI data stored in the IM-SSF. If per-CSI tracing is enabled, then the IM-SSF will generate more trace output whenever that CSI is applied to an incoming INVITE.

Ability to override per-MSISDN lookup of CSI

The IM-SSF uses the MSISDN (extracted from the INVITE) to lookup appropriate CSI. If an alternate approach is required, several IM-SSF features allow overriding the normal CSI lookup behaviour.

Ability to override method for classifying the trigger and originating or terminating

The IM-SSF looks for a parameter in the incoming Route to classify a call. The parameter to look for, and the expect value, are completely configurable. Can also override this mechanism entirely, making the classification externally (outside the IM-SSF, for example by using signaling interceptors in the SIS).


See Using the IM-SSF for more details on using the additional IM-SSF features.

See IM-SSF in Action for details on how IM-SSF istriggered, looks up subscription information, classifies the call as originating or terminating, and runs the BCSM.

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