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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 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.


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. Use our Diameter Dictionary to assist in setting up Cx/Dx testing scenarios.

CSCF Testing (Server Emulation)

dsTest, Developing Solutions, Cx Interface, CSCF Testing, IMS Testing, VoLTE TestingThe HSS emulator executes procedures based on configurable subscriber profiles, responding to requests and reports 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 deregister 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 deregistration

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

SmartEvents — Alter application behavior or coordinate multiple interface applications with SmartEvents. Our programmable, subscriber-level state machine gives you the ability to define handlers for specified application events that can then cause an event in another application to be executed. You can also configure handlers to modify subscriber information during run-time, introduce timers, or randomize subscriber behavior based on configurable probabilities to name a few of the many options in one of dsTest’s most powerful features.

SmartMessageElement — Insert, delete, or replace elements in Diameter, RADIUS, MAP, LDAP, GTP, REST or SOAP messages with our SmartMessageElement solution. Define proprietary signaling or corrupt elements to facilitate negative testing. You can specify when your elements are used with SmartEvents.

Traffic Profile — Draw the shape of your test actions across time with Traffic Profile. You can define the rate for any action as a static rate or reference a Traffic Profile configuration, which also means that multiple Traffic Profiles can be running currently. Use Traffic Profile in conjunction with the randomizing features in SmartEvents to design a test that more truly simulates real-world network activity.

Diameter Dictionary — Define a set of message templates against which all messages will be validated with our Diameter Dictionary. Whether you’re load testing or testing functionality all messages are validated.

Operational Measurements

dsTest provides rich sets of measurements for the Cx Interface application:

  • Transaction and transport layer attempts, successes, and failures
  • Transaction duration, transactions-per-second, and round-trip delay
  • Message and byte counters
  • Errors encountered and error indications received in messages

See our Online Help for Cx measurements, Diameter measurements, and socket measurements.

You can read more about the reporting features offered with dsTest and dsClient here.

Supporting Standards