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Press Release: Analog Terminal (FXO) and Network Port (FXS) Testing Using
tProbe™ Client Server

Gaithersburg, Maryland, USA - September 17, 2012- GL Communications Inc. announced today the release of its enhanced tProbe™ with FXO/FXS ports that can also support dual T1 E1 ports, dual datacom ports, dual VF In/Out ports, and an Ethernet port.

Speaking to reporters, Mr. Jagdish Vadalia Senior Manager of Product Development for the company said, “FXS and FXO are ports used by analog phone lines or phones. A Foreign Exchange Subscriber (FXS) port supplies ring voltage, battery current, dial tone and voice signals. Foreign Exchange Office (FXO) delivers an on-hook/off-hook indication (loop closure), DTMF digits, voice signals, and is usually a phone or fax machine.”

He added, “The FXO and FXS ports on GL’s tProbe™ unit simulates all of the above features. Also, the FXO port on the tProbe permits non-intrusive capture and analysis of voiceband signals from a two-wire telephone line.”

Mr. Vadalia explained, “In a typical testing scenario of tProbe™ FXO Port to Mobile or Landline Phone , the call flow depicts the call from tProbe™ FXO port to the Landline or Mobile phone through the wall jack FXS, local PBX, and central office of the service provider and base station. With the tProbe™ FXO call script, one can perform the basic operations during the call setup such as the Off-hook/On-hook, check dial tone, transmit DTMF digits, monitor ring signal, and handling traffic.

In a testing scenario of tProbe™ FXS Port to a Regular 2-wire Phone, the call flow depicts the call from tProbe™ FXS port to regular phone (2-wire phone) via RJ-11 cable. This test places the ring to regular phone (2-wire phone), captures the incoming traffic into the file and transmits traffic to the other end. With the tProbe™ FXS call script, one can perform the basic operations during the call setup such as monitoring Off-hook/On-hook, send dial tone, monitor DTMF digits, send ring signal and handling traffic.”

Main Features

  • Script based simulation of 2-Wire Telephone Port (FXO) and Telephone Wall Jack (FXS).
  • GUI based testing of basic functions for FXO/FXS.

Functions supported by FXO port

  • ON hook and OFF hook (loop closure)
  • Transmit and Capture Traffic (digits, tones, and voice)
  • 2-Wire Calling/Answering, Caller ID, T1 E1 to 2-Wire FXO Drop or Insert, PC to 2-Wire FXO Drop or Insert

Functions supported by FXS port

  • Detection of "ON hook" and "OFF hook" status
  • Ring and Battery Voltage Generation, Dial Tone Generation
  • Transmit and Capture Traffic (digits, tones, and voice)
  • T1 E1 FXS Drop or Insert, PC to 2-Wire FXS Drop or Insert
  • Loudspeaker provided, to hear the voice being transmitted on FXO/FXS ports.
  • FXO/FXS termination for over 70 countries with different termination characteristics.


  • Testing gateways, VoIP ATAs, telephone lines, handsets
  • Voice quality testing, 2wire call automation, Caller ID
  • Monitoring signaling, voice, and tones on telephone lines non-intrusively
  • Generation and reception of traffic on 2-wire telephone lines
  • Remote operation of FXO FXS ports over TCP/IP

For comprehensive information on the application, please refere to the tProbe™ with FXO/FXS ports webpage.

About GL Communications Inc

Founded in 1986, GL Communications Inc. is a leading supplier of test, monitoring, and analysis equipment for TDM, Wireless, IP and VoIP networks. Unlike conventional test equipment, GL's test platforms provide visualization, capture, storage, and convenient features like portability, remotability, and scripting.

 GL’s TDM Analysis & Emulation line of products includes T1, E1, T3, E3, OC-3, OC-12, STM-1, STM-4, analog four-wire, and analog two-wire interface cards, external portable pods, and complete system solutions. Capabilities include voiceband traffic analysis and emulation across all traffic types (voice, digits, tones, fax, modem), all protocols (ISDN, SS7, GR-303, Frame Relay, HDLC, V5.X, ATM, GSM, GPRS, LTE, etc.), and with capacities up to thousands of channels. Our newest products provide astonishing capacity and capture capability up to and including gigabit speeds.

GL’s VoIP and IP products generate / analyze thousands of calls and traffic simultaneously with traffic types such as frames, packets, voice files, digits, video, tones, noise, and fax.  Almost all codecs are supported including G.711, G.729, AMR, EVRC-A,B,C, GSM, iSAC,  and many more. Additional features include visual analysis, real-time listening, and recording. The product line also includes Ethernet / IP Testing capability that simulates and checks frame transport and throughput parameters of Ethernet and IP networks, including delay, errors and other impairments.

 GL's Voice Quality Testing (VQT) product line complements all of GL's products. Using ITU-standard algorithms (PAMS, PSQM, and PESQ), GL's VQT provides a widely accepted solution for assessing voice quality in the telecom industry. Voice Quality Testing across multiple networks (T1, E1, T3, E3, OC-3, OC-12, VoIP, Wireless, and Landline) are all available.
GL’s Wireless Products perform protocol analysis and voice quality assessment on GSM, CDMA, UMTS, and LTE networks. Connections can be made to any wireless phone with automated call control, GPS mapping and real-time signal measurements.

GL’s Echo Canceller testing solutions provide the broadest range of simulation and analysis, including line and acoustic echo. GL’s compliance testing per G.168. G.167, and P.340 across TDM, IP, VoIP and Wireless networks is widely accepted in the industry.

GL’s wireless VQT solutions help assessing impairments to voice quality such as poor mobile phone quality, voice compression and decompression algorithms, delay, loss and gain in speech levels, noise, acoustic and landline echo, and other distortions are easily assessed and accurately measured.

GL’s Handheld data testers can test a wide variety of communications facilities and equipment including T1, fractional T1, E1, fractional E1, T3 and E3 modems, multiplexers, CSU, DSUs, T1 CSUs, DTUs, NTUs and TIUs and more. The testers provide convenience, economy, and portability for almost any interface, including RS232, RS-422, RS-530, X.21, T1, E1, T3, E3, and many others.

GL’s Network Surveillance and Monitoring products include Probes for TDM, IP, VoIP, ATM, and Wireless networks. An open standards based approach provides a scalable, feature rich, real-time access to network characteristics.  Centralized or distributed access, efficient transport and database loading allow compatibility with 3rd party and standards based monitoring systems.

For more information about GL's complete line of products,


Shelley Sharma
Phone: 301-670-4784 ext. 114

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