Phone: (469) 634-4200

Cx Interface, Developing Solutions, dsTest, CSCF Testing, IMS Testing, VoLTE Testing, HSS Testing

dsTest supports server emulation and client interface simulation capabilities for the 3GPP Diameter Cx/Dx Interface.  Test Interrogating Call Session Control Function (I-CSCF) and Serving Call Session Control Function (S-CSCF) Cx interfaces in LTE and UMTS networks with our Home Subscriber Server (HSS) Emulator.  Use a CSCF node with our Cx Interface application to test the capacity and performance of an HSS.  Use the Dx Interface Application to test your Server Location Function (SLF).  The Cx/Dx reference points are stateless, and are specified in 3GPP TS  29.228.

Our Cx/Dx interface application, along with the comprehensive set of dsTest’s  EPC and IMS interface applications, such as  Rx, Sh/Dh, Ro/Gy, Rf/Gz,  and SIP interface signalling simulation between IP Multimedia Services (IMS) nodes, dsTest provides full featured end-to-end testing capabilities for 3G/4G/5G packet core networks, including IMS and Voice over LTE (VoLTE) testing.

Use the HSS Emulator and Cx/Dx Client Simulator in tandem to test Diameter Routing Agents (DRA), Proxies, Relay Agents, and Redirect Agents.  For more information regarding how to use dsTest for Diameter functional and compliance testing, see our page on Conformance Testing.

Comprehensive sets of operational measurements for the Cx Interface, Diameter, and socket level are collected at configurable intervals and stored in a SQLite database on the dsTest server.  Real-time measurements may be retrieved through our dsClient CLI interface or graphed via our dsClient GUI interface.


The Cx application implements the following procedures:

  • User registration status query
  • Authentication
  • S-CSCF registration/de-registration notification
  • Network-initiated de-registration
  • User location query
  • Update of user profile

A complete set of events that can be generated with the Cx/Dx interface can be found here, and our Diameter Dictionary can be used assist in setting up, executing, and verifying Cx/Dx testing scenarios.

CSCF Testing (Server Emulation)

The HSS emulator executes procedures based on configurable subscriber profiles, responding to requests and repordsTest, Developing Solutions, Cx Interface, CSCF Testing, IMS Testing, VoLTE Testingts from CSCFs and eliminating the need to dedicate a production server to lab activities.  You can execute a test event chain with a run-time command or during an automated test to initiate the Cx De-register procedure.

Read more about our HSS Emulator.

HSS Testing (Client Simulation)

The Cx Interface application can be used as a CSCF simulator to determine the impact of new IMS features and standards before they are deployed in a network.  The Cx Interface application allows users to validate HSS performance and capacity in a realistic network environment, replicating the deployment configuration.

Execute timed chains of test events with a run-time command or during an automated test to trigger CSCF-initiated procedures.

  • User status and location queries
  • S-CSCF registration
  • Authentication vector requests
  • S-CSCF de-registration

Multiple CSCF nodes can be instantiated on a single server, each with scalable subscriber loads and transaction rates. In this mode the Cx interfaces of up to 1000 independent nodes may be simultaneously simulated.  The nodes are fully independent and their subscriber configurations may be independent, overlap, or be duplicated.

Read more about dsTest Capacity and Performance.

SLF Testing

The Cx/Dx Interface application can be used as a CSCF simulator to test the performance and capacity of your Server Location Function (SLF) before it is deployed in your network.

Advanced Testing Features

Enhance your testing with Developing Solutions advanced testing features:

  • Insert, delete, or replace AVPs in your messages with our SmartAVP solution.  SmartAVP enables you to define proprietary signaling or to corrupt AVPs to facilitate negative testing.
  • Configure commands to define the series of actions and rates that each subscriber takes. Advanced profiles can be created using SmartEvents to define a mix of traffic based on probability assignments.  With SmartEvents, you can specify when your SmartAVPs are used.
  • Define a set of message templates against which all messages will be validated with our  Diameter Dictionary.  Every Diameter message is validated, even under load conditions.

Read more about our Advanced Diameter Testing Features.

Supporting Standards