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Newsletter: GL Announces the Release of RTP Toolbox™

Welcome to the February issue of GL Communications' Newsletter providing information about new introductions in GL Communications' VoIP Testing products.

IP technology holds the promise of converging voice, video, and data onto one transport technology. Up till now, VoIP (Voice over IP) has lagged behind due to nagging problems in voice quality and ease of use when compared to circuit switched or wireless voice technology. Delay, jitter, packet loss and other impairments are still far too common in VoIP. This is about to change as IP matures and develops efficient techniques to handle real-time data such as Ipv6, advanced RTP, and RTCP XR.

RTP (Real-time Transport Protocol) and RTCP (Real-time Control Protocol) provide end-to-end network transport and monitoring functions suitable for applications transmitting real-time data such as audio, video, or simulation data, over multicast or unicast network connections. RTCP includes information for Packet Loss, Jitter, Delay, Signal Level, Call, Quality Metrics, Echo Return Loss and more. These two protocols will be the dominant methods for transporting voice over IP. Tools to effectively test these protocols are sorely needed.

RTP ToolBox™, a new introduction among GL Communications' VoIP testing tools, is designed not only to monitor these RTP and RTCP packets, but also to allow users to manually create and terminate RTP sessions using a user-friendly GUI, independent of call-signaling protocols such as SIP, H323, MEGACO, or MGCP.

Depicted below are typical RTP functions that can be tested using RTP Toolbox


RTP ToolBox™ can be used for

  • Testing and developing enhanced voice features (VAD, Echo Cancellation, Codec, Digit Regeneration, Digit Generation, Fax over IP, Jitter Implementation etc) within end-user equipment (IP Phones, ATA, MTA etc).
  • Testing media gateway telephony interfaces.
  • End-to-End network testing before and during VoIP deployment.
  • Automated testing of Digital Signal Processing embedded into network elements.

A brief summary of features introduced in RTP ToolBox™:

  • Digits, Tones Generation and Detection

    The RTP ToolBox™ application can be used to generate various in-band tones and digits. The supported tones include single, dual, and multitones; supported digits include DTMF, MF, and MFR2 forward and backward digits. Complimentary to the signal generation, the application allows users to capture tones and digits in the traffic. It displays additional information about the captured signal such as type of the signal, timestamp, event, power, frequencies, on-time and off-time as shown in the screenshots given below:


  • RTP Event Generation and Detection

    In addition to in-band digits, the application allows generation and detection of out-of-band digits (DTMF, MF) and events (such as Answering tone, Calling tone, Special Dial tone etc) as per the RFC 2833 standard.

  • Synchronous Tx/Rx Utility

    This feature allows the user to transmit and receive an aufio file simultaneously on a session, and serves the purpose of synchronizing multimedia streams. This functionality is also useful when performing echo cancellation tests, per G.168.

  • Play to Speaker and Talk using Microphone

    The RTP ToolBox™ can analyze traffic in real-time by playing the stream to a speaker using 'Play to Speaker (or Audio Play)' feature. Further, with the 'Talk using Microphone (or Audio Wave In)' feature, it is also possible to generate real-time voice data using the default audio device's microphone input or to communicate to another party at the other end of the RTP stream using a headset.

  • Playback from File and Record Data to File

    The Playback from File (or Send File) feature in RTP ToolBox™ is used to send recorded voice files such as *.wav and *.pcm to the destination port. It allows user to choose the type of codec before transmitting the voice file. In addition to Send File option, the application can record the incoming data on a session to a particular file in *.wav or *.pcm format. Both applications are necessary to perform Voice Quality Assessment using ITU-standard algorithms such as PESQ.


  • Other In-band Statistics

    Many real-time and historical statistics are present within the application. Such statistics include jitter, delay, missing packets, duplicate packets, out-of-order packets, power, frequency, signal to noise ratio, dc offset, byte and frame counts, RTCP information and much more.

  • Supports Industry Standard Codecs

    RTP ToolBox™ supports standard codecs such as G711 (mu-Law and A-Law), GSM (Full Rate), G.729a, G.726 (All Rates), AMR, and more.

  • Oscilloscope and Spectrum Analyzer views

    Using the scalable oscilloscope view, the signal of any selected session can be graphically displayed in real-time as a function of time. Further, the data received on a specified receive timeslot can be viewed in the spectral domain (spectral amplitude vs frequency).

    In this case, a Fast Fourier Transform (FFT) is applied to successive sample sets of the incoming data and is displayed graphically. The frequency resolution can be adjusted based on the value of FFT length (from 32 points to 8192 points). The spectral view also displays information such as Total Power, Tone Power and Frequency, Noise Power and Signal-to-Noise ratio as shown in the following screenshots:


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