IP/VoIP Protocol Simulators

Core Network Simulators

LTE IMS (IP Multimedia Services) Emulator

Simulate multiple UEs and IMS core elements using Session Initiation Protocol (SIP) to package voice, video, data, fixed, and mobile services on a single platform to users



Internet Protocol (IP) Multimedia Subsystem, popularly known as “IMS”, is built on Session Initiation Protocol (SIP) to  package voice, video, data, fixed, and mobile services on a single platform to users. It provides a unique convergence platform for different types of networks – whether it is mobile, satellite, broadband, cable or fixed networks, with the goal of building an efficient interoperating network.

GL’s MAPS™ SIP IMS test suite provide a full-fledged network environment that enables users to test their applications, devices, and services prior to deployment on a real-time network. It can simulate all or specific elements within IMS network infrastructure using simple ready-to-use test bed setups.

The application is available as:

  • MAPS™ SIP IMS Protocol Emulator (Item # PKS127)

The network architecture shown above outlines the IMS Core Network elements which can be simulated using GL's MAPS™ SIP IMS test tool.

MAPS™ SIP IMS test suite can simulate multiple UEs and IMS core elements such as P-CSCF, I-CSCF, S-CSCF, PCRF, MGCF and IP-SM-GW which provides the IMS core network. With the help of mobile phones, and other simulated wireless networks, the VoLTE lab can be operated in real-time for making VoLTE calls, SMS calls and also for interworking with PSTN and VoIP networks. It includes ready-to-use scripts, as per IETF specification. Test scripts include general messaging and call flow scenarios for multimedia call session setup and control over IP networks. Logging and pass/fail results are also reported. Test cases verify conformance of actions such as registration, call control, proxies and other servers.

MAPS™ IMS Multi Interface emulator can simulate end-to-end online and offline charging procedures, interacting with SIP (UEs) and Diameter (OCS, OFCS) interfaces.

Few of the IMS network entities and their functionalities are:

  • P-CSCF – receives requests from UE and then serves the request or forwards it to other servers
    • a SIP proxy
    • first point of contact for the IMS terminal
    • discovers its P-CSCF
    • locates I-CSCF for the user
    • provides subscriber authentication
  • I-CSCF – acts as contact point in the operator’s network
    • forwards SIP request or response to the S-CSCF
    • Used for SIP functions such as Registration
  • S-CSCF – maintains sessions for the registered users
    • central node of the signaling plane
    • handles SIP registrations, routing services, enforces the policy
  • IP-SM-GW (IP Short Message Gateway)
    • network element provides the interconnection between GSM-UMTS network and LTE-EPC network for sending and receiving SMS.

MAPS™ can be used to simulate all of the interfaces listed above in an IMS network. A single MAPS™ can act as more than one entity at a time and generating required messages in the network.

MAPS™ SIP IMS Emulator includes ready-to-use scripts, as per IETF specification. Test scripts include general messaging and call flow scenarios for multimedia call session setup and control over IP networks. Logging and pass/fail results are also reported. Test cases verify conformance of actions such as registration, call control, proxies and other servers.

The application gives the users the unlimited ability to edit protocol specific messages and control scenarios (message sequences). "Message sequences" are generated through scripts. "Messages" are created using message templates.

GL’s IMS Protocol Analyzer within PacketScan™- All IP Protocol Analyzer is capable of real-time capturing, decoding and analyzing SIP signaling and RTP media for live systems as well as the Diameter signaling used for accessing subscriber data and charging data on IMS networks. PacketScan™ permits continuous monitoring of communication over IMS - S6a, S6d, S13, Cx/Dx, Gx, Rx, Sh, Gy/Ro interfaces. Other interfaces such as Rf, Dh, Gq, Zh, Zn, Wa, Wd, Wx, Wm, Wg, Pr will also be supported by the application in near future.


  • Simulates P-CSCF, I-CSCF, S-CSCF, PCRF, HSS, BGCF, MGCF and IP-SM-GW elements in LTE IMS network supporting Cx/Dx, Rx, Gx, Gm, Mw, SGi, Mi, and Mj interfaces
  • Simulate multiple UEs
  • Supports IMS multi interface configuration simulating end-to-end Online and Offline charging procedures
  • Supports both signaling and traffic simulation (RTP from simulated UE's and GTP from Real UE's) between any two IMS nodes
  • Supports simulation of core network, access network, roaming architecture, interworking with other networks
  • Supports generation and verification of CS domain traffic over LTE-IMS, including VoLTE (Voice), and SMS services.
  • Complete IMS lab for End to End test solution.
  • Test environment allows user to test each IMS network elements independently using single interface simulation or multi interface simulation
  • Any of the network element within the lab environment can be replaced by DUT to test particular node working
  • Integrate IMS core network easily with 2G, 3G, 4G or any PSTN networks to test any call scenario using remote MAPS™
  • Build customized call scenarios as MAPS™ provides complete script-based solution
  • Test any applications and services using IMS core network
  • Remote control/monitor  all the interwork interfaces and elements using Remote MAPS™ application
  • Cost effective solution

Supported Protocols Standards

Supported Protocols Standard / Specification Used
SIP RFC 3261
SIP Extensions RFC 3262 - Reliability of Provisional Responses in the Session Initiation Protocol (SIP)
RFC 3311 - The Session Initiation Protocol (SIP) UPDATE Method
RFC 3455 - Private Header (P-Header) Extensions to the Session Initiation Protocol (SIP) for the 3rd-Generation Partnership Project (3GPP)
RFC 3515 - The Session Initiation Protocol (SIP) Refer Method
RFC 3310 - HTTP/SIP Digest Authentication Using Authentication and Key Agreement (AKA)
RFC 3263 - Session Initiation Protocol (SIP): Locating SIP Servers
Diameter RFC 3588 - Diameter Base Protocol
S6a, S6d, S13 - 3GPP TS 29.272 V10.3.0
Rx - 3GGP TS 29214-b10
Cx/Dx - 3GPP TS 29.228 & TS29.229
Gx - 3GPP TS 29.212 & TS 23.203

IMS Call Simulation

GL's MAPS™ SIP IMS supports simulation of all the nodes to achieve an end-to-end call simulation over LTE - IMS network. A Voice over LTE call can happen within the same network or between 2 different service providers.

The following are the possible call scenarios which are supported using MAPS™ SIP IMS emulator:

  • IMS Registration via SIP interface (with AKA Authentication, with Digest authentication) over TCP/UDP
  • IMS Registration from Visited Network
  • Mobile induced deregistration - SIP
  • SIP Audio Call from Non Roaming user to Non Roaming user across the network
  • SIP Audio Call from Non Roaming user to Non Roaming user on the same network
  • SIP Audio Call from Roaming user to Non Roaming user across the network
  • SIP Audio Call from Roaming user to Non Roaming user on the same network
  • Call from IMS to PSTN
  • SMS Call from IMS (4G) to UMTS (2G/3G)
  • Registration and IMS call with Signaling Compression (sigcomp)

Call between UEs in different networks

The following network is an illustration of a Call simulation from Non Roaming User to another Non Roaming User across different LTE – IMS Network (UE1 in ATT network to UE2 in Verizon network).

End-to-end Call from Non Roaming User to Non Roaming User Across the Network

As depicted in the diagram above, each node in the LTE-IMS network can be configured and controlled testing can be performed using a single Remote MAPS™ Server.

The Remote MAPS™ Server feature within MAPS™, is a client server module, designed for multi-node multi-interface simulation. In IMS network, MAPS™ can be configured to simulate multiple nodes situated at various locations, which can be controlled using a single Remote Client GUI. The client application connects to the server and remotely accesses the MAPS™ functionalities simulating the configured nodes. The client communicates with the remote MAPS™ Server via the Listener running at the server location.

Remote MAPS™ Server Configuration

A single remote MAPS™ server can configure and test each node in the LTE-IMS network as shown above.

UE1 in ATT network and UE2 in Verizon network

Below diagram shows the Registration flow at S-CSCF which handles SIP Registrations and routing services for ATT Network. S-CSCF is a multi-interface interacting with I-CSCF and HSS.

Registration at S-CSCF of ATT Network

Below diagram shows the Call flow at I-CSCF which finds the S-CSCF of Verizon Network serving UE2 by contacting the HSS and routing the request to required S-CSCF. I-CSCF is a multi-interface interacting with S-CSCF of ATT Network, HSS and S-CSCF of Verizon Network.

Call at one of the IMS core elements (I-CSCF of Verizon Network)

The following networks shows other various call scenarios supported by MAPS™ SIP IMS

Call from UE1 in ATT Network to UE2 in the Same Network

Call from UE1 in ATT Network to UE2 in PSTN Network

SMS Call from IMS to UMTS (2G/3G) Network

GL’s MAPS™ SIP IMS emulator can emulate functions of an IP-SM-GW network element in order to push or pull SMS from LTE-EPC to SMSC over IP/IMS network.

SMS Call over LTE Procedure

In SMS over IMS communication, SMS is encapsulated in a SIP message and carried over IMS core network to SMSC. The IP Short Messaging Gateway (IP-SM-GW) network element provides the interconnection between GSM-UMTS network and LTE-EPC network for sending and receiving SMS.

The image below depicts the call flow for transmission of encapsulated SMS messages over LTE via IMS elements

SMS Call at SSCSF Node

SMS Call at IP-SM-GW Node

call flow of SMS messages over LTE

End-to-End Online and Offline Charging Simulation

The IMS network architecture outlining the IMS Core Network elements interconnected with SIP elements can be simulated using GL's MAPS™ IMS Multi Interface test tool.

End-to-End Charging System Test Setup using MAPS™

MAPS™ IMS Multi Interface is designed to simulate end-to-end Online and Offline Charging procedures. This above setup depicts MAPS™ CSCF Multi-Interface node configured to handle end-to-end charging procedures.

MAPS™ S-CSCF Multi Interface node interacts with the MAPS™ SIP (UEs) receiving the request and responding using SIP protocol. Registration and Authentication of the UEs is performed at MAPS™ Diameter (HSS). And MAPS™ S-CSCF interacts with the OCF for processing Online charging procedure and with the OFCS for processing Offline charging procedure. MAPS™ Diameter is configured as the charging systems (OCS and OFCS) for Rf and Ro (DCCA) interfaces. 

Online Session Charging with Unit Reservation (SCUR)

A typical credit-control process makes use of several interrogations (INITIAL_REQUEST, UPDATE_REQUEST, and TERMINATION_REQUEST) during online session charging for unit reservations.
The screen depicts MAPS™ IMS Multi Interface (S-CSCF) simulating end-to-end online charging procedure receiving the charging request from UE (MAPS™ SIP) and forwarding it to OCS (MAPS™ Diameter) for credit request processing. The initial UE registration and authentication is processed at HSS node (MAPS™ Diameter).

Session based Online Credit Control Procedure

Offline Session Charging

A typical Session based offline charging is the process of reporting usage reports for a session and uses the START (Initial), and STOP (Terminate) accounting data. During a session, a Network Element may transmit multiple ACR Interims' depending on the proceeding of the session.

The end-to-end offline charging procedure can be simulated with MAPS™ IMS Multi Interface configured as S-CSCF receiving requests from UEs (MAPS™ SIP). The UEs are registered and authenticated at HSS (MAPS™ Diameter), the call is established between the UEs. The Multi Interface S-CSCF forwards the offline charging ACR request to CDF (MAPS™ Diameter) where the credit request is processed.

Session based Offline Charging Procedures

General MAPS™ Features

  • Call Simulation
    • Multi-protocol, Multi-interface Simulation
    • Script based and protocol independent software architecture
    • Auto generate and respond to signaling messages
    • Traffic Handling Capabilities (requires additional license)
    • Fault Insertion, and Erroneous Call Flows Testing
  • Automation
    • Automated Load /Stress Testing
    • Scheduler and pre-saved configuration files for automated testing
  • Pre-processing tools
    • Easy script builder for quick testing to advance testing
    • Customization of test configuration profiles
    • Unlimited ability to customize the protocol fields and call control scenarios  
  • Centralized Control and Remote Access
    • Command Line Interface (requires additional license)
    • Option to send reports to database accessible via web interface
    • Centralized control of multiple MAPS™ applications remotely from single client application
  • Reports and Statistics
    • Call Status, Link Status, and Message Statistics
    • User defined Statistics for RTP Traffic parameters
    • Capture Events, and Error Events

Call Simulation and Control

The signaling and traffic simulation in a call is completely implemented using scripts. Commands in the scripts are executed in controlled way to simulate protocol and traffic behavior. Most of the commands used in the scripts are generic and independent of specific protocol.

MAPS™ application acts as either the Caller or resides at the network terminal acting as Callee. The Call Generation feature simulates an outgoing call by sending call control messages to the DUT using scripts and profiles. The profiles allow necessary parameters of call control messages to be changed during runtime. Call generated from other entity can be automatically detected in call reception window by pre-setting the required answer scripts in the Incoming Call Handler.

The call control scripts can also automatically handle the traffic over the established call. MAPS™ supports transmission and detection of various traffic types over IP (RTP, GTP), ATM, & TDM - such as, digits, voice file, single tone, dual tones, fax, sms, email, http, ftp, IVR, audio and video quality. MAPS™ also includes support for wide range of codec rates – visit www.gl.com/traffic-simulation.html and www.gl.com/voice-codecs.html webpage for more details.

Message Sequence - Each call scenario provides the trace with full decoding of the messages exchanged between the MAPS™ and the DUT, and graphical ladder diagrams of the call flow with time stamp. Impairments can be applied to messages to simulate error conditions that occur in real-time networks.

Event-Driven Control - Scripts execution, being event-based, allows redirection of script execution on-the-go with user-defined events. The custom parameters in the events can also be changed during script execution using event profiles.

Script Contents & Script Flow - The script flow and the contents window displays the Script Name, Sub-script Name, Script line number, and script statements to be successfully executed, which help the users in troubleshooting a particular call scenario.

Bulk Call Simulation and Load Testing

MAPS™ supports automated stress/load testing capabilities through Load Generation and Bulk Call Simulation features. Bulk Call Simulation allows quick configurations to easily create multiple test entries with different scripts and profiles. Multiple tests can be run simultaneously or sequentially (queue up tasks in succession). Load generation feature further allows specifying the patterns with which the bulk calls can be generated. Load generation can be customized with different statistical distribution patterns such as Uniform, Ramp, Sawtooth, Fixed, Normal, Step, and Step-Sawtooth distribution. Call duration also can be randomized using similar statistical distribution. This feature also helps users configure Stress/Load Testing parameters such as Call per second (CPS), Max Active Call, Minimum and Maximum Call Rates, Start Call Rates, and other parameters.


Scheduler can be used to schedule the simulation of bulk calls or manual calls at a specific start time. The pre-saved master configuration files for test setup and call simulation are automatically loaded to automate the test procedure.

Customization of Test Setup Parameters

The test setup profiles (.xml files) allow users to configure the necessary parameters in order to establish communication between MAPS™ and the DUT. It includes configuring parameters of the network nodes, the network properties, and transport related configurations such as T1/E1 timeslots, IP Address and port numbers for both MAPS™ and the DUT.

Once the transport layer is configured properly, protocol specific signaling messages and traffic can be transmitted and received successfully. All parameters setup in test setup are global and are accessible to all scripts. These parameters initialize protocol engines and the transport modules specific to the protocol.

Customization of Test Parameters, Call Flow, and Protocol Messages Using Pre-Processing Tools

  • Message Editor - The Message Templates (GL’s proprietary *.HDL files) comprises of protocol encoding parameters with preset values. It is required to create a message template for every message in a protocol. The message templates are called within the scripts to perform scenario based testing.
  • Profile Editor – Profiles (*.xml files) are used to change the values of the fields in the messages (i.e. Message Template in MAPS™) during the course of a call. The multiple profiles with varying parameter values that allow users to configure call instances in call generation and to receive calls.
  • Script Editor - The script editor allows the user to create / edit scripts and to define variables for the fields in the messages. The script uses pre-defined message templates to build call flow and perform send and receive actions. Script editor provides options to run the test for multiple iterations in sequential or random flow. Commands allow retransmission of messages with specific interval.

Command Line Interface

Supports scripting through a Command Line Interface (CLI) such as the Python, and TCL, using MAPS™ client-server functionality (requires additional license)

MAPS™ can be configured as server-side application, to enable remote controlling of the application through multiple command-line based clients. Supported clients include C++, TCL, Python and others. TCL provides a simple scripting language, with programming facilities such as looping, procedures, and variables. The TCL Client application includes a MapsTclIfc.dll file, a packaged library that enables communication with the Server from a TCL environment.

User can remotely perform all functions such as start test bed setup, load scripts and profiles, apply user events such as send digits/file/tones, detect digits/file/tones, dial, originate call, terminate call, start and stop traffic and so on. User can also generate and receive calls through commands. This client application is distributed along with MAPS™ Server application. Multiple MAPS™ CLI servers can be controlled remotely from single client application (such as TCL, Python, etc).

Call Statistics, Events, Link Status

Call Status & Message Statistics - By default, all call handling scripts (irrespective of the type of the functions) are assessed by MAPS™ to provide statistical information about Total Calls, Active Calls, Completed Calls, Passed Calls, Failed Calls, and Calls/Sec. It is also possible to categorize the statistical information as per the call handling scripts. In addition, Call Generation and Call Reception windows provide useful call status & script execution results.

In addition, Message Stats option for any specific protocol, logs number of times the messages are being transmitted (Tx Count) and received (Rx Count), thus allowing user to monitor the occurring events.

User Defined Statistics – Users can customize the global statistics for RTP audio and video traffic. These global parameters are defined in the call generation scripts, which are calculated and updated periodically on run time.

Events Reporting – MAPS™ provides Event Log, Error Events, and Captured Errors windows that log the captured events and errors encountered during the progress of the call.

Link Status - Link Status window indicates transport related information of the protocol, for example, if SCTP is used as transport, it indicates if the association is Up or Down in the Link Status window. MAPS™ IuCS ATM uses SSCOP transport and the associated link status is indicated as Up or Down in the Link Status window.


Please Note: The XX in the Item No. refers to the hardware platform, listed at the bottom of the Buyer's Guide, which the software will be running on. Therefore, XX can either be ETA or EEA (Octal/Quad Boards), PTA or PEA (tProbe Units), UTA or UEA (USB Units), HUT or HUE (Universal Cards), and HDT or HDE (HD cards) depending upon the hardware.