800 Series AEX800/TDM800P User Manual 601-00008A Rev.
Digium, Inc. 445 Jan Davis Drive Huntsville, AL 35806 United States Main Number: 1.256.428.6000 Tech Support: 1.256.428.6161 U.S. Toll Free: 1.877.344.4861 Sales: 1.256.428.6262 www.digium.com www.asterisk.org www.asterisknow.org © Digium, Inc. 2009 All rights reserved. No part of this publication may be copied, distributed, transmitted, transcribed, stored in a retrieval system, or translated into any human or computer language without the prior written permission of Digium, Inc. Digium, Inc.
Safety Certification and Agency Approvals Safety: US/CSA 60950 IEC 60950 EN 60950 Other: CE Mark 2002/95/EC Restrictions on Hazardous Substances (RoHS), 2005/747/EC lead free exemption (Annex C) Telecom: FCC Part 68, ANSI/ITA-968-A, Including Amendment A1 and A2 EMC: FCC Part 15 Class A EN55022/CISPR22 Class A EN55025 IEC 61000 Digium, Inc.
Federal Communications Commission Part 68 This equipment complies with Part 68 of the FCC rules and the requirements adopted by the ACTA. On the back of the 800 Series printed circuit board is a label that contains, among other information, a product identifier in the format US:AAAEQ##TXXXX. If requested, this number must be provided to the telephone company.
The telephone company may make changes in its facilities, equipment, operations or procedures that could affect the operation of the equipment. If this happens, the telephone company will provide advance notice in order for you to make necessary modifications to maintain uninterrupted service. If you experience problems with your 800 Series card, contact Digium, Inc. at 1.877.DIGIUM.1 (1.877.344.4861) for repair and/or warranty information.
Introduction to 800 Series Documentation This manual contains product information for the 800 Series card. Be sure to refer to any supplementary documents or release notes that were shipped with your equipment. The manual is organized in the following manner: Chapter/ Appendix Title Description 1 Overview Identifies the card and type of modules you received with your 800 Series card. This chapter covers applications and uses of the 800 Series card in the real world.
Symbol Definitions Caution statements indicate a condition where damage to the unit or its configuration could occur if operational procedures are not followed. To reduce the risk of damage or injury, follow all steps or procedures as instructed. The ESD symbol indicates electrostatic sensitive devices. Observe precautions for handling devices. Wear a properly grounded electrostatic discharge (ESD) wrist strap while handling the device.
Important Safety Instructions User Cautions Warning This card must be used with the PC lid screwed down. Telecommunications network voltages exist inside the PC! The PC must be shut down and telecommunications line connection shall be removed before opening the PC. Electrical Shock. To reduce the risk of injury, damage to the unit or your equipment, do not attempt to touch the modules while they are powered. The case should be securely closed before power is applied to the unit. Alarm Dialing Equipment.
User Cautions Caution. This card is not intended for home use. It must be used in restricted access locations and installed in UL Listed I.T.E. only. Static Electricity. To reduce the risk of damaging the unit or your equipment, do not attempt to open the enclosure or gain access to areas where you are not instructed to do so. Refer servicing to qualified service personnel. Save these instructions for future reference. Service Personnel Cautions Warning. This card must be used with the PC lid screwed down.
Service Personnel Cautions Caution. This card is not intended for home use. It must be used in restricted access locations and installed in UL Listed I.T.E. only. Digium, Inc.
TABLE OF CONTENTS Chapter 1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Echo-Cancellation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 What is Asterisk®? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Asterisk as a Switch (PBX) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Asterisk as a Gateway . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table Of Contents Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 Driver Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39 Configuring Card Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 Voicemail . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 Dial Plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
List of Figures Figure 1: Figure 2: Figure 3: Figure 4: Figure 5: Figure 6: Figure 7: Figure 8: Digium, Inc. Sample Card Application . . . . . . . . . . . . . . . . . . . . . 15 TDM800P Card with Four Single Modules . . . . . . . . 23 AEX800 Card with Two Quad Modules . . . . . . . . . .24 Motherboard Slots . . . . . . . . . . . . . . . . . . . . . . . . . . 28 Insert the Card . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29 Connect Power for FXS Modules . . . . . . . . . . . . . . .
List of Tables Table 1: Table 2: Table 3: Table A-1: Table B-2: Digium, Inc. Example TDM800P Card Configurations. . . . . . . . . 25 Example AEX800 Card Configurations . . . . . . . . . . 26 Card Identifiers . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 RJ11 Telco Port Connector . . . . . . . . . . . . . . . . . . . .57 Maximum Power Consumption . . . . . . . . . . . . . . . . .
Chapter 1 Overview The 800 Series cards are versatile devices used for connecting your phone network to the PSTN (Public Switched Telephone Network) world. This is accomplished through phone lines connected to the FXO (Foreign Exchange Office) ports and phones connected via the FXS (Foreign Exchange Station) ports. The cards allow Asterisk to connect to your phone network, creating an office type telephony environment.
Chapter 1: Overview Echo-Cancellation Users connecting their 800 Series cards to the PSTN or other devices are likely to be placing calls that will result, at some point, in an unbalanced 4-wire/2-wire hybrid. The result of this hybrid is the reflection of a nearend echo to the calling party. Elimination of this echo is the responsibility of echo cancellation. The 800 Series cards, unless otherwise equipped, utilize Asterisk to perform software-based echo cancellation.
Chapter 1: Overview What is Asterisk®? Asterisk is the world’s leading open source telephony engine and tool kit. Offering flexibility unheard of in the world of proprietary communications, Asterisk empowers developers and integrators to create advanced communication solutions...for free. Asterisk is released as open source under the GNU General Public License (GPL), and it is available for download free of charge.
Chapter 1: Overview Asterisk as a Feature/Media Server Need an IVR? Asterisk’s got you covered. How about a conference bridge? Yep. It’s in there. What about an automated attendant? Asterisk does that too. How about a replacement for your aging legacy voicemail system? Can do. Unified messaging? No problem. Need a telephony interface for your web site? Ok. Asterisk in the Call Center Asterisk has been adopted by call centers around the world based on its flexibility.
Chapter 2 Card Installation This chapter provides the following information: Unpacking the Card on page 20 Shipment Inspection on page 21 Module Identification on page 21 Port Identification on page 21 Card Identification on page 25 FXS and FXO Connection on page 27 Slot Compatibility on page 27 Hardware Installation on page 29 Software Installation on page 32 Installing Asterisk on page 36 Digium, Inc.
Chapter 2: Card Installation Unpacking the Card When you unpack your card, carefully inspect it for any damage that may have occurred in shipment. If damage is suspected, file a claim with the carrier and contact the reseller from which the card was purchased, or contact Digium Technical Support at 1.256.428.6161. Keep the original shipping container to use for future shipment or proof of damage during shipment. Note: Only qualified service personnel should install the card.
Chapter 2: Card Installation Shipment Inspection The following items are included in shipment of an 800 Series card: 800 Series card (TDM800P or AEX800) FXO and/or FXS module(s) (depending on configuration) Module Identification The 800 Series cards ships with FXO and/or FXS modules in place. These are identified by their color. Take a moment to identify which modules were shipped with your card.
Chapter 2: Card Installation appropriate identification of these ports. The port identification is the same for all cards in this series. It is important to identify the type and location of your 800 Series modules. You will need this information during the Asterisk configuration. The ports available for use on the 800 Series cards are not continuous. The ports available for use depend upon the type of module used, and the placement of the module on the card.
Chapter 2: Card Installation 5 1 Single Modules 2 6 All Ports Available 8 Power Supply Figure 2: TDM800P Card with Four Single Modules If a quad module is placed covering single module ports 1 and 2, then that module will use ports 1-4. Likewise, if a quad module is placed covering single module ports 3 and 4, the module will use ports 5 through 8. Figure 3 shows a AEX800 with two quad modules. Digium, Inc.
Chapter 2: Card Installation 5 6 7 Quad 1 Modules 2 3 4 8 All Ports Available Power Supply VPMADT032 Echo Cancellation Module Figure 3: AEX800 Card with Two Quad Modules Digium, Inc.
Chapter 2: Card Installation Card Identification There are multiple configurations in which an 800 Series card may be purchased. Each configuration consists of a combination of single modules, quad modules, or both, and may also include the VPMADT032 echo cancellation module. See Table 1 on page 25 for a list of the most common TDM800P configurations. See Table 2 on page 26 for a list of the most common AEX800 configurations.
Chapter 2: Card Installation Table 2: Example AEX800 Card Configurations FXO/FXS Ports Card ID AEX801B 1 FXO module AEX804B 4 FXO modules AEX808B 8 FXO modules AEX844B 4 FXS and 4 FXO modules AEX880B 8 FXS modules Digium, Inc.
Chapter 2: Card Installation FXS and FXO Connection The 800 Series cards provide eight RJ11 connectors for access to the FXS and/or FXO modules installed in the available slots. The diagram in Table A-1 on page 57 provides the pinout for this connector. Caution. Only qualified service personnel should continue with hardware installation and configuration of the 800 Series card. Users should not attempt to perform these functions themselves.
Chapter 2: Card Installation Slots 0 1 2 3 4 Figure 4: Motherboard Slots The TDM800 card is a 32-bit 33MHz card keyed for universal 3.3 volt or 5.0 volt operation and works in any PCI 2.2 (or greater) compliant slot. This means that in the motherboard shown in Figure 4, the TDM800 card will fit into Slots 1, 2, or 3 (PCI slots), but will not fit into Slot 0 (AGP slot) or Slot 4 (PCI Express slot). The AEX800 card is a PCI Express card. Slot 4, illustrated above, is a 1 lane (X1) PCI Express compliant slot.
Chapter 2: Card Installation Hardware Installation 1. Now that you are acquainted with your card, power down your computer and unplug it from its power source. 2. Attach a static strap to your wrist and open the case. 3. Remove the bracket place holder and insert the card into a PCI (TDM800P) or PCI Express (AEX800) slot. See Figure 5. Figure 5: Insert the Card 4. If your card has any FXS modules, you will also need to connect the power cable from your computer’s power supply to the back of the card.
Chapter 2: Card Installation Figure 6: Connect Power for FXS Modules Many modern PCs and servers do not have either spare or any 12V power connectors. If you have FXS modules on your card and your computer does not have power cables available, then power must be provided to the 800 Series card by an alternate means. Digium provides a solution to this problem with the optional PWR2400B (available separately).
Chapter 2: Card Installation be purchased. The shorting strap on the PWR2400B should be removed if a second power supply is used. The PWR2400B does not connect to any bus inside the computer. It may be used wherever there is an available PCI-size bracket such as a PCI, PCI Express, or AGP slot. Note: The PWR2400B is not intended to supply power to any other device, it is intended only to be used with UL Listed Digium analog cards. 5. Replace the cover to your computer. Electrical Shock.
Chapter 2: Card Installation Software Installation Digium hardware requires drivers and libraries that are not integrated with the Linux kernel. Digium hardware is only supported under Linux. Digium recommends CentOS, Debian, Red Hat, and Ubuntu distributions of Linux. However, many other distributions are supported by Digium Technical Support. Digium’s software, including drivers and application software, may be obtained from Digium’s download server at: http://downloads.digium.
Chapter 2: Card Installation installed any of these, Digium recommends that you upgrade to the latest “-current” version of each. Note: If you are using the 1.4.x series of Asterisk, you will need Asterisk 1.4.22 or newer. 1. After the machine has booted to Linux, log in and execute the following command to list the devices detected by the PCI bus: # lspci -n Confirm that the output from lspci lists a device with Digium’s PCI vendor ID which is “d161”.
Chapter 2: Card Installation Table 3: Card Identifiers Model TDM800P AEX800 Identifier 0800 8002 A Digium 800 Series (TDM800P/AEX800) card identifier should be listed. If a matching card identifier is not listed, then your machine is not PCI 2.2 (or higher) or PCI Express compatible, and the card will not work with your motherboard. 2. Download the latest DAHDI drivers with tools. DAHDI is available for download from: http://downloads.digium.
Chapter 2: Card Installation 3. Expand the downloaded file, compile its contents, and install the drivers and tools. Substitute the version of DAHDI for the X.X.X in the command lines below. # # # # # tar -zxvf dahdi-linux-complete-current.tar.gz cd dahdi-linux-complete-X.X.X+X.X.X make make install make config Note: Executing ‘make config’ will install an init script and symlinks which will allow you to start and stop DAHDI as a service. Digium, Inc.
Chapter 2: Card Installation Installing Asterisk If you wish to use Asterisk with your new hardware, you can follow the instructions below. 1. Download the latest release version of Asterisk, either 1.4.22 (or later) or 1.6.0.1 (or later). Substitute the version of Asterisk for the X.X in the command below. Asterisk is available for download from: http://downloads.digium.com/pub/telephony/asterisk # wget http://downloads.digium.com/pub/telephony/ asterisk/asterisk-X.X-current.tar.gz 2.
Chapter 2: Card Installation 3. If this is the first Asterisk installation on this system, you should install the sample configuration files. To do this, run: # make samples Note: Running this command will overwrite, after making a backup copy, any older Asterisk configuration files that you have in the /etc/ asterisk directory. If your installation has failed, it may be because you are missing one or more of the build dependencies, the kernel headers, or the development tools.
Chapter 3 Configuration The 800 Series cards have a variety of configuration options. This chapter provides sample configurations to demonstrate customizing the Asterisk software to meet your individual needs. Each section explains basic options as examples. Once you have familiarized yourself with the samples, you can edit the configuration files to meet your specific needs. Digium, Inc.
Chapter 3: Configuration Driver Configuration 1. Begin by opening the system.conf file from the /etc/dahdi directory. 2. Specify the two letter country code for your loadzone and defaultzone. This will preload tone zone data and specify a default tone zone for your interfaces. The following is a typical setup for a telco in the US: loadzone = us defaultzone = us Digium, Inc.
Chapter 3: Configuration 3. Specify the channel definitions. The format is: = A list of valid devices are specified in the sample system.conf file. If your card has any red FXO modules, add the following to system.conf: fxsks = fxsks uses kewlstart signalling, which is loopstart signalling with disconnect supervision.
Chapter 3: Configuration 4. If your card has any green FXS modules, add the following: fxoks = fxoks uses kewlstart signalling, which is loopstart signalling with disconnect supervision. For example, a TDM880E card would be configured as the following: fxoks = 1-8 OR fxoks = 1,2,3,4,5,6,7,8 5. An example TDM844E card configuration would be: fxoks = 1-4 fxsks = 5-8 OR fxoks = 1,2,3,4 fxsks = 5,6,7,8 6. DAHDI uses modular echo cancellers that are configured per channel.
Chapter 3: Configuration system.conf file if you do not have hardware echo cancellers and need echo cancellation. The format is: echocanceller = , A list of valid echo cancellers are specified in the sample system.conf file. The following is a typical setup using software-based echo cancellation: echocanceller = mg2,1-8 7. Load DAHDI drivers into the kernel using the modprobe utility. The appropriate driver for the 800 Series cards is wctdm24xxp.
Chapter 3: Configuration Figure 7: Example dmesg Screen Shot Note: Output as shown above may vary depending on the 800 Series card you use. Digium, Inc.
Chapter 3: Configuration Configuring Card Features You will need to modify the chan_dahdi.conf file which is located in the /etc/asterisk directory in order to configure the essential features of your card. This file is the configuration layer between DAHDI and Asterisk. The following is a sample configuration for a TDM844E card. You can place this at the bottom of your chan_dahdi.conf file.
Chapter 3: Configuration channel = 5-8 Users of Digium's hardware echo cancellation module, the VPMADT032, should set the echocancel option to "yes." The module will automatically configure itself to run at full capacity, 1024 taps (128ms), on each channel. Users without the VPMADT032 using open source echo cancelers included with DAHDI should configure echocancel to the values 128 (16ms) or 256 (32ms). Setting "yes" will default the option to 128 (16ms).
Chapter 3: Configuration Voicemail Open voicemail.conf and find the following line at the bottom: [default] 1234 => 4242,Mark Spencer,root@localhost In this example, 1234 is the mailbox number, 4242 is the password, Mark Spencer is the person’s name, and root@localhost is his email address. You can add extensions by adding the following: 1000 => 1234,Moose Member,moose@digium.com 2000 => 1234,Bill Savage,bsavage@digium.com Digium, Inc.
Chapter 3: Configuration Dial Plan Open extensions.conf, which contains a large, complex sample dial plan. In this step, you will configure a basic dial plan to enable you to send and receive calls.
Chapter 3: Configuration In this example there are two internal extensions (1000 and 2000), a number to check voicemail (8500), a number to listen to music-on-hold, (8501), and a prefix to dial to get an outside line (9). It is configured to accept incoming calls over the FXO, rings phones 1 and 2, and route to voicemail box 1000. Testing Your Configuration 1. Start Asterisk by typing: asterisk 2. Connect to Asterisk and view the output by typing: asterisk -vvvvr 3.
Chapter 3: Configuration Figure 8: Sample Application Note: More detailed information is provided at the Asterisk website (www.asterisk.org), as well as the Digium Knowledge Base (kb.digium.com). You may also obtain assistance by contacting Digium Technical Support at 1.256.428.6161 or visiting the website at www.digium.com. Digium, Inc.
Chapter 4 FXS and FXO Explained Identification There are multiple standard configurations in which an 800 Series card may be purchased. Each configuration consists of one to four FXS and/or FXO modules. These modules are identified by their color. FXS - Foreign Exchange Station (Green Modules) FXO - Foreign Exchange Office (Red Modules) This chapter provides an in-depth review of the two module types and their uses within your Asterisk server.
Chapter 4: FXS and FXO Explained Using Your 800 Series Card Connect the outside line to an FXO port on your Asterisk server to receive voltage from the outside lines. Connect the phones to FXS ports on your Asterisk server. When the FXO module in your Asterisk Server receives the voltage, it will then generate voltage using the FXS module and send it to your analog phone. Digium, Inc.
Chapter 5 Troubleshooting This chapter provides frequently asked questions and possible resolutions as identified by Digium Technical Support. Multiple resources are available to obtain more information about Asterisk and Digium products. Please visit both www.digium.com and www.asterisk.org for more information. Digium, Inc.
Chapter 5: Troubleshooting The FXO module never seems to hang-up the line. How do I set it to hang-up? Set busydetect = yes and busycount = 10 in the chan_dahdi.conf for your channels. This will cause the line to hang-up by listening for a consecutive number of busy tones. Upon editing chan_dahdi.conf, you will need to restart Asterisk. I have echo problems on my FXO modules and I've tried the different echo cancellation algorithms in dahdi_config.h, tried tweaking the gains, and still nothing works.
Chapter 5: Troubleshooting There are several options available to correct this. Each involves editing the chan_dahdi.conf file. Be sure to restart Asterisk upon completion. 1. Adjust echocancel = yes to one of the following values: 32, 64, 128, or 256. 2. You can also set echotraining = yes. 3. You can also adjust the rxgain and the txgain, although it is only recommended to shift between -5 and 5.
Chapter 5: Troubleshooting Common Fixes 1. Check to see if the X Window System (e.g. X.Org Server) is running by entering the following: # ps aux | grep X If the X Window System is running, stop the application since it may cause a conflict with Asterisk. 2. Check to see if your PATA IDE hard drives are running with DMA levels set. Advance user can perform an hdparm on your hard drive interface.
Chapter 5: Troubleshooting Where can I find answers to additional questions? There are several places to inquire for more information about Asterisk Digium products: 1. Digium Technical Support (+1.256.428.6161), or Toll Free in the U.S. (1.877.344.4861), is available 7am-8pm Central Time (GMT -6), Monday - Friday. 2. Asterisk users mailing list (asterisk.org/lists.digium.com). 3. IRC channel #asterisk on (irc.freenode.net).
Appendix A Pin Assignments All eight ports on the 800 Series card’s bracket are 6-pin RJ11 ports. The pin assignments are identified in Table A-1. Table A-1: RJ11 Telco Port Connector Digium, Inc.
Appendix B Specifications This appendix provides specifications, required environmental conditions, and maximum power consumption for the 800 Series cards. Physical (All Cards). Size: Weight: 6.48” × 4.2” × 0.68” (16.46 x 10.67 x 1.72 cm) PCB size, does not include the PCI bracket. Check your model carefully to be sure it will accept this PCI card. 4.5 oz (127.58 gm) with no modules loaded Each quad module adds 1 oz (28.35 g) Interfaces. Local Loop Access: Industry standard 6-pin RJ-11.
Appendix B: Specifications Environment. Temperature: 0 to 50° C (32 to 122° F) operation -20 to 65° C (-4 to 149° F) storage Humidity: 10 to 90% non-condensing Note: Operating temperature is limited to 0 to 40° C (32 to 104°F) when used with optional PWR2400B Power Bracket Hardware and Software Requirements. 500-Mhz Pentium III or better 64MB RAM Available PCI or PCI-Express Slot (as described previously) Power Consumption.
Appendix B: Specifications Table B-2: Maximum Power Consumption Model Digium, Inc. Power 3.3V All TDM models 1W 3.3V All AEX “B” models 3.5 W 3.3V All AEX “E” models 4.5 W 5.0V All TDM “B” models 1W 5.0V All TDM “E” models 9W 5V All AEX models 0W 12V AEX/TDM804E 0W AEX/TDM808E into 1REN 0W AEX/TDM844E into 2REN 6.5W AEX/TDM840E into 3REN 6.
Appendix C Glossary and Acronyms ANSI American National Standards Institute An organization which proposes and establishes standards for international communications. asynchronous Not synchronized; not timed to an outside clock source. Transmission is controlled by start bits at the beginning and stop bits at the end of each character. Asynchronous communications are often found in internet access and remote office applications.
Appendix C: Glossary and Acronyms broadband Broadband transmission shares the bandwidth of a particular medium (copper or fiber optic) to integrate multiple signals. The channels take up different frequencies on the cable, integrating voice, data, and video over one line. channel A generic term for an individual data stream. Service providers can use multiplexing techniques to transmit multiple channels over a common medium. Cat5 Category of Performance for wiring and cabling.
Appendix C: Glossary and Acronyms CO central office The CO houses local switching equipment. All local access lines in a particular geographic area terminate at this facility (which is usually owned and operated by an ILEC). CPE customer premises equipment Terminal equipment which is connected to the telecommunications network and which resides within the home or office of the customer. This includes telephones, modems, terminals, routers, and television set-top boxes.
Appendix C: Glossary and Acronyms DS3 Digital Signal, Level 3 T3 in North America and Japan, E3 in Europe. Up to 672 voice channels (DS0s). DS3/T3/E3 lines are not part of the PSTN. DTMF Dual Tone Multi-Frequency Push-button or touch tone dialing. E1 The European equivalent of North American T1, transmits data at 2.048 Mbps, up to 32 voice channels (DS0s). E3 The European equivalent of North American T3, transmits data at 34.368 Mbps, up to 512 voice channels (DS0s). Equivalent to 16 E1 lines.
Appendix C: Glossary and Acronyms FXS Foreign Exchange Station Initiates and sends ringing voltage. Phones are connected to the FXS ports on the 800 Series card. G.711 A recommendation by the Telecommunication Standardization Sector (ITU-T) for an algorithm designed to transmit and receive mulaw PCM voice and A-law at a digital bit rate of 64 Kbps. This algorithm is used for digital telephone sets on digital PBX. G.723.
Appendix C: Glossary and Acronyms iLBC internet Low Bitrate Codec A free speech codec used for voice over IP. It is designed for narrow band speech with a payload bitrate of 13.33 kbps (frame length = 30ms) and 15.2 kbps (frame length = 20 ms). ILEC incumbent local exchange carrier The LECs that were the original carriers in the market prior to the entry of competition and therefore have the dominant position in the market. interface A point of contact between two systems, networks, or devices.
Appendix C: Glossary and Acronyms MGCP Media Gateway Control Protocol multiplexing Transmitting multiple signals over a single line or channel. FDM (frequency division multiplexing) and TDM (time division multiplexing) are the two most common methods. FDM separates signals by dividing the data onto different carrier frequencies, and TDM separates signals by interleaving bits one after the other. MUX multiplexer A device which transmits multiple signals over a single communications line or channel.
Appendix C: Glossary and Acronyms of fixed-line analog telephone systems, the PSTN is now almost entirely digital, and now includes mobile as well as fixed telephones. PPP point-to-point protocol Type of communications link that connects a single device to another single device, such as a remote terminal to a host computer. PSTN public switched telephone network A communications network which uses telephones to establish connections between two points. Also referred to as the dial network.
Appendix C: Glossary and Acronyms T1 A dedicated digital carrier facility which transmits up to 24 voice channels (DS0s) and transmits data at 1.544 Mbps. Commonly used to carry traffic to and from private business networks and ISPs. T3 A dedicated digital carrier facility which consists of 28 T1 lines and transmits data at 44.736 Mbps. Equivalent to 672 voice channels (DS0s).
Appendix C: Glossary and Acronyms V volts VoIP Voice over IP Technology used for transmitting voice traffic over a data network using the Internet Protocol. Digium, Inc.
