TC400 Series
TCE400 / TC400B
User Manual
601-00007 Rev. B3
445 Jan Davis Drive NW
Digium, Inc.
Huntsvil le, 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. 2013
All rights reserved.
No part of this publication may be copied, distributed, transmitted, transcribed, stored in a
retri eval s yst em , or t ran sl ated i nt o a ny huma n or compu te r lan gu ag e with ou t t he pr io r wri tte n
permission of Digium, Inc.
Digium, Inc. has made every effort to ensure that the instructions contained in this document
are ade q uate an d err o r free. The manufa ctu r e r w i ll, if n ec es s ary , expl ai n is su es w h ic h m ay
not be covered by this documentation. The manufacturer’s liability for any errors in the
docume nts is limi ted to the correctio n of errors and the aforementioned advis ory services.
This doc ument h as been p repar ed for us e by profe ssiona l and pr operly tr ained p ersonn el,
and the cus to m er as su m es fu ll re sp onsibi li ty w he n us in g it.
Adobe and Acrobat are registered trademarks, and Acrobat Reader is a trademark of Adobe
Systems Incorporated.
Asterisk, Digium, Switchvox, and AsteriskNOW are registered trademarks and Asterisk
Business Edition, AsteriskGUI, and Asterisk Appliance are trademarks of Digium, Inc.
Any other trademarks mentioned in the document are the property of their respective owners.
Digium, Inc. Page 2
Compliance Information
Compliance information for this product is available at
http://www.digium.com/ccs-compliance.
Digium, Inc. Page 3
Introduction to TC400 Serie s Documentation
This manual cont ains product information for the TC400 Serie s cards. Be
sure to refer to any supplementa ry documents or release notes that were
shipped with your equipment. The manual is organized in the following
manner:
Chapter/
Appendix
1
2
3
4
A
B
Title Description
Overview Identifies the features of your car d. This chapter
Card Installation Provides instructions for installing the card in your
Configuration Provides examples for configuring options.
Questions an d
Answers
Specifications Details card specifications.
Glossary and
Acronyms
covers applications and us es of the TC400 Series in
the re al w o r l d.
PC, acquiring correct drivers, and checking device
compatibility.
Explains resolutions to common problems and
frequentl y as ked questions per taining to card
installation and usage.
Defines terms related to this product.
Digium, Inc. Page 4
Symbol Definitions
Caution stat emen ts in dicate a c onditio n whe r e d amage to t he un it o r
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 sym b o l in d i ca t es electrostat i c s en si ti ve d e vi ces. Obser v e
prec autions for handling devices. Wear a properly ground ed
electrostatic discha rge (ESD) wrist strap while handling the device.
The Electrical Hazard Symbol indicates a possibility of electrical
shock when operat ing this unit in certain situations. To reduce the
risk of damage or injury, fol low all steps or proc edures as
instructed.
Digium, Inc. Page 5
User Cautions
Power Source.
The outlet should be installed near the eq uipment and be easily
accessible.
Applying Power.
Use only the power cord, power supply, and/or bat teries indicate d in
the manual. Do not dispose of batteries in a fire. The may explode.
Check with local codes for special disposal instructions.
Installation
This car d is for use only with compatible UL Listed computers that
have Install ation Instructions detailing installation of car d cage
accessories.
Servicing.
Do not attempt to service this card unless specifically instructed to do
so. Do not attempt to remove the card from your equipment while
power is present. Refe r ser vicing to qualified service personnel.
Water and Moisture.
Do not spill liquids on this unit. Do not operate this equipment in a
wet environme nt.
Important Safety Instructions
Heat.
Do not operate or store this product near heat sources such as
radiators, air ducts, areas subject to direct, intense sunlight, or other
products that produce heat.
Static Electricity.
To reduce the risk of damaging the unit or your equipment, do not
attempt to open the e nclosure or ga in acc es s to areas where you ar e
not instructed to do so. Refer servicing to qualified service personnel.
Save these instructions for future reference.
Digium, Inc. Page 6
TABLE OF CONTENTS
Chapter 1
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
Chapter 2
Card Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
Chapter 3
Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29
What is Asterisk®? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Asterisk as a Switch (PBX) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Asterisk asa Gateway . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Asterisk in the CallCe nter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Asterisk in the Network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
Asterisk Everywhere . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
Unpacking the Card . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
Shipment Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
Slot Compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
Hardware Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
Software Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
Installing DAHDI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25
Installing Asterisk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27
Chapter 4
Questions and Answers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
Digiu m, In c . Page 7
Table Of Contents
Appendix A
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33
Appendix B
Glossary and Ac ronyms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3 5
Digium, Inc. Page 8
List of Figures
Figure : Sample Telco Application . . . . . . . . . . . . . . . . . . . . .12
Figure : Sample Network Application . . . . . . . . . . . . . . . . . . . 13
Figure : TC400B Card . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
Figure : TCE400 Card . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
Figure : Motherboard Slots . . . . . . . . . . . . . . . . . . . . . . . . . .20
Figure : Insert the Card . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
1
2
3
4
5
6
Digium, Inc. Page 9
List of T able s
Table A-1: Maximum Power Consumption . . . . . . . . . . . . . . . . .34
Digium, Inc. Page 10
Chapter 1 Overview
The TC400 Series cards are a bundle of the half-length, low-profile
TC400P (PCI) or TCE400 (PCI-E) base card and the TC400M voice
processing module. The TC400 Series cards are designed to handle, in
dedicated DSP resources, the complex codec translations for highly
compressed audio as would otherwise b e processed by Asterisk in
software.
Asterisk, in software and with Digium® G.729a licensing, is capable of
transforming the G.729a codec into other codecs for th e purposes of call
origination or termination, bridging disparate calls, or VoIP to TDM
connectivity. These transformations in software are very expensive, in
terms of MIPS, and require a substantial amount of CPU time to
accomplish. A TC400 Series card not only relieves the CPU of this duty ,
freeing it up to handle other tasks or t o complet e additional call
processing; but also provide s Asterisk with the capability of bridgi ng
G.723.1 compressed audio into other formats, a capability not previously
possible.
The TC400 Series cards decompress G.729a (8.0 Kbit) or G.723.1 (5.3
Kbit and 6.3 Kbit) into u-law or a-law; or, compress u-law or a-law into
G.729a (8.0 Kbit) or G.723.1 (5.3 Kbit and 6.3 Kbit). The TC400 Series
cards are rated to handle up to 120 bi-directional G.729a transformations
or 92 bi-directional G.723.1 transf ormations. The TC400 Series cards do
not require additiona l licensing fees for the use of these codecs nor do
Digiu m, In c . P age 1 1
Chapter 1: Overview
they require the registration process associated with Digium's softwarebased G.729a codec licensing.
Features:
120 channels of bi-direct ional G.729a (8 Kbit) transcoding
or
92 channels of bi-directional G.723.1 (5.3 Kbit and 6.3 Kbit) transcoding
Figure 1: Sample Telco Application
Digium, Inc. Page 12
Chapter 1: Overview
Figure 2: Sample Network Application
Digium, Inc. Page 13
What is Asteri sk®?
Chapter 1: Overview
Asterisk is th e world’s leading open source t elephony engine and tool kit.
Offering fle xibility unheard of in the world of proprietar y
communications, Asterisk empowers developers and integr ators to create
advanced communication solutions...for free. Asterisk is r eleased as open
source under the GNU General Public License (GPL), a nd it is available
for download free of charge. Asterisk is the most popular open source
software avai lable, with the Asterisk Community being the top infl uencer
in VoIP.
Asterisk as a Switch (PBX)
Asterisk can be configured as th e core of an IP or hybrid PBX, switching
calls, managing routes, enabling features, and conne ct ing callers with the
outside world over IP, analog (POTS), and digital (T1/E1) connections.
Asterisk runs on a wide variety of opera ting systems including Linux,
Mac OS X, OpenBSD, FreeBSD, and Sun Solaris. It provides all of the
features you would exp ect from a PBX inclu ding many advanced f eatu res
that are often associate d with high end (and high cost) proprietary PBXs.
Asterisk's archi tecture is designed for maximum flexibilit y and supports
Voice over IP in many protocols, and can interoperate with almost all
standards-base d telephony equipment using relatively ine xpensive
hardware.
Asterisk as a Gateway
It can also be built out as the heart of a media gateway, bridging the
legacy PSTN to the expanding world of IP telephony. Asterisk’s modular
architecture a llows it to co nvert betwee n a wide ran ge of communicat ions
protocols and media codecs.
Digium, Inc. Page 14
Asterisk as a Feature/Media Server
Chapter 1: Overview
Need an IVR? Asterisk’s got you covered. How about a conference
bridge? Yep. It’s in there. What ab out an automated attendant? Asterisk
does that too. How about a replacement for your agi ng 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. Call center and contact center developers have built complete
ACD systems based on Asterisk. Asterisk has also added new life to
existing call center solutions by adding remote IP agent capabilities,
advanced skills-based routing, predictive and bulk dialing, and more.
Asterisk in the Network
Internet Telephony Service Providers (ITSPs), competitive local
exchange c arriers (CLECS ) and even fi rst- tier i ncu m be nts h av e
discovered the power of open source communications with Asterisk.
Feature servers, hosted services clusters, voicemail systems, pre-paid
calling solution s, al l based on Asterisk have helped reduce costs and
enabled flexibility.
Aste risk Everywhere
Asterisk has become the basis for thousands of communications
solutions. If you need to communicate, Asterisk is your answer. For more
information on Asterisk visit http://www.asterisk.org or http://
www.digium.com.
Digium, Inc. Page 15
Chapter 2 Card Installation
This chapter provides the following information:
Unpacking the Card on page 17
Sh i pm en t Ins pec ti o n on page 17
Slot Compatibility on page 20
Hardware Installation on page 22
Software Installation on page 23
Note: The TC400 Series card installation instructions are written so
that they will apply to any card in the series. E xamples and card
specific inf ormation are includ ed as needed.
Digiu m, In c . Page 16
Unpacking the Card
Chapte r 2 : C ar d I n st a lla t io n
When you unpack your card, carefully inspect it for any damage that may
have occurred in shipment. If damage is sus pected, file a claim with the
carrier and contact your reseller from which the card was purchased, or
Digium T ec hnical Support (+1. 256.428. 6161). Kee p the origina l shi pping
container to use for future shipment or proof of damage during shipment.
Note: Only qualified service personnel should install t he card. Users
should not attempt to perform thi s function.
Shipmen t Ins pec ti o n
The following items are includ ed in the shipment of the TC400 Series
card:
A TC400B or TCE400 card
TC400M voice processing module (installed on TC400B or TC400
card)
Caution.
Only qualified service per sonnel should continue with har dware
installation and configuration of the TC400 Series car d. Us ers
should not attempt to perform these functions. This card is for
use in Listed I.T.E. (information technology equipment) only.
Digium, Inc. Page 17
Chapte r 2 : C ar d I n st a lla t io n
Keyed for
3.3 or 5 volt PCI
TC400M
voice
processing
module
Figure 3: TC400B Card
Digium, Inc. Page 18
Figure 4: TCE400 Card
Chapte r 2 : C ar d I n st a lla t io n
Digium, Inc. Page 19
Slot Compatibility
Slots
0
1
2
3
4
Chapte r 2 : C ar d I n st a lla t io n
Check the type of card you received to be sure it is compatible with your
PCI slot. To determine which slot you have, identif y it by comparing it to
those shown in the figure below.
Slot Number:
0: AGP Pro Slot
1: 64-bit 5.0 volt PCI Slot
2: 64-bit 3.3 volt PCI Slot
3: 32-bit 5.0 volt PCI Slot
4: PCI Express Slot
Figure 5: Motherboard Slots
Digium, Inc. Page 20
Chapte r 2 : C ar d I n st a lla t io n
The TC400B 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 Figur e 5, the TC400B car d will
fit into Slots 1, 2, or 3 (PCI slots) but will not fit into Sl ot 0 (AGP slot).
The TCE400 card is a PCI Express card. Slot 4, illustrated above, is a 1
lane (X1) PCI Express complia nt slot. The TCE400 will work in any PCI
Express compliant slot, includi ng lane length s X1, X4, X8, and X16. This
means that in the motherboard shown in Figur e 5, the TCE400 wil l only
fit into Slot 4. The TCE400 can not be used in Slots 0 through 3.
Digium, Inc. Page 21
Chapte r 2 : C ar d I n st a lla t io n
Hardware Installat ion
1. 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 the PCI or
PCI Express slot. See Figure 6.
Figure 6: Insert the Card
4. Replace the cover to your computer.
Digium, Inc. Page 22
Software Installation
Chapte r 2 : C ar d I n st a lla t io n
Digium hardware requires drivers and libraries that are not integrate d
with the Linux kernel. Digium hardware is only supported under Linux.
Digium recommends CentOS, Debian, R ed Hat, and Ubuntu di stribut ions
of Linux. However, m any other distributions are support ed by Digium
Technical Support.
Digium’s software, including drivers and application software, may be
obtained from Digium’s download server at:
http://downloads.digium.com
For an introduction to Asterisk, Digium’s telephony software, including
additional infor mation on its configuration, setup, and fea tures, please
refer to:
http://www.asterisk.org
For the latest information on se tting up and configuring DAHDI drivers
for your Digium hardwar e product, please refer to t he lat est relea se of t his
manual which is available fro m the product-specific documentation
section at:
http://www.digium.com
T o install your TC400 Series card, you will need:
Linux 2.6 kernel headers
Development libraries and headers for ncurses
Development libraries and headers for zlib and openssl
Development libraries and headers for newt
GCC and standard software build tools
Digium, Inc. Page 23
Chapte r 2 : C ar d I n st a lla t io n
It is recommended that you use the most recent version of the Asterisk
and DAHDI software for the best results. If you have previously installed
either of these, Digium recommends th at 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.
Digium, Inc. Page 24
Chapte r 2 : C ar d I n st a lla t io n
Installing DAHDI
1. Download the latest DAHDI drivers with tools. DAHDI is available
for download from:
http://downloads.digium.com/pub/telephony/dahdi-linux-complete
# wget http://downloads.digium.com/pub/telephony/
dahdi-linux-complete/dahdi-linux-complete-current.
tar.gz
2.
Expand the dow nl oad ed file , compile its content s, an d ins tal l 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 symli nks
which will allow you to start and stop DAHDI as a service.
3. Load DAHDI drivers into the kernel using the modprobe utility. The
appropriate driver for a TC400 Series c ard is
# modprobe wctc4xxp
Digium, Inc. Page 25
wctc4xxp.
Chapte r 2 : C ar d I n st a lla t io n
4. Confirm that the card was started successfully by running the dmesg
command.
# dmesg
The end of the output should look similar to the following:
dahdi_transcode: Loaded.
wctc4xxp: tc400b0: Attached to device at 0000:00:0a.0.
wctc4xxp: tc400b0: (G.729a / G.723.1) Transcoder support LOADED (firm ver
= 6.12)
wctc4xxp: tc40 0b0: I nstalled a Wildcard TC: Wil dcard TC400P+TC400M
dahdi_transc ode: Registered codec transl ator 'DTE Encoder' with 92
transcoders ( srcs=0000000c, dsts=00000101)
dahdi_transc ode: Registered codec transl ator 'DTE Decoder' with 92
transcoders ( srcs=00000101, dsts=0000000c)
Digium, Inc. Page 26
Installing Asteris k
Chapte r 2 : C ar d I n st a lla t io n
If you wish to use Asterisk with your new hardware, you can follow the
instructions below.
1. Download the latest release version of Asterisk, eith er 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 d ownload from:
http://downloads.digium.com/pub/telephony/asterisk
# wget http://downloads.digium.com/pub/telephony/
asterisk/asterisk-X.X-current.tar.gz
Expand the dow nl oad ed file , compile its content s, an d ins tal l the
2.
application. Substitute the version of Asterisk for the X.X and X.X.X
in the command lines below.
# tar -zxvf asterisk-X.X-current.tar.gz
# cd asterisk-X.X.X/
# ./configure
# make menuselect
# make
# make install
Digium, Inc. Page 27
Chapte r 2 : C ar d I n st a lla t io n
3. If this is the fir st Asterisk i nsta llat ion o n this s yste m, yo u should insta ll
the sample configurati on files. To do this, r un:
# make samples
Note: Running this command will overwrite, after making a backup
copy, any older Asterisk configura tion 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 kerne l headers, or the
development tools. Please contact your reseller where the card was
purchased, or call Digium Technical Support (+1.256.428.6161) for
assistance.
Note: Complete instructions for installing Asteri sk are available at
www.asterisk.org.
Digium, Inc. Page 28
Chapter 3 Configuration
No changes to system.conf or chan_dahdi.conf ar e necessary to utilize this
card. The ‘mode’ module parameter may be used to specify whe ther the
card can be used to transcode G.729a, G.723.1, or both.
mode = mixed - This default option will enable 92 calls of G.729a or
G.723.1 (5.3 Kbit and 6.3 Kbit)
mode = g729 - This option will enable 120 calls of G.729a
mode = g723 - This option will enable 92 calls of G.723.1 (5.3 Kbit
and 6.3 Kbit)
The 'mode' module parameter may be set in either /etc/modprobe.conf or
/etc/modprobe.d/dahdi.conf, depending on the Linux distribution, by
adding a line similar to the following:
options wctc4xxp mode=g729
Then execute “/etc/init.d/dahdi reload” for this change to tak e effect.
Note: Asterisk must not be running in order for this to be successful.
Digiu m, In c . Page 29
Testing Your Configur ation:
1. Start Asterisk by typing:
# asterisk -vvvvc
Chapter 3: Configuration
2.
Verify that the TC400 Series is registered with Asterisk by issuing the
following command on the Asterisk CLI.
*CLI> transcoder show
This should display the number of encoder s and decoders registered
by the TC400 Series card.
Digium, Inc. Page 30
Chapter 4 Questions and Answ ers
This chapter provides frequently asked questions as identified from
Digium Technical Support and possible resolutions. Multiple resources
are available to obtain more information about Asterisk and Digium
products. These resources are listed on page 32.
Q: My card can’t seem to reach its full channel count, why?
A: See next answer.
Q: Asterisk issues errors such as "rtp.c: Unable to allocate socket: Too
many open files." How can I prevent this?
A: Each call that uses a TC400 Series card for transcoding requires two
file handles. Increase the maximum number of open file descriptors
allowed on your system using the ulimit utility . F irst, log into a Linux
shell as the use r running the asteri sk process (i.e. usually root). Check the
current maximum by executing
executing ulimit -n [limit] (e.g. ulimit -n 32768).
Q: Does my card take 1000 interrupts per second like my other Digium
cards?
A: A TC400 Series card only takes interrupts when it is in an active
transcoding state, and will not pull interrupts when it is idling. This is
different be havior than Digium analog and digital interfa ce car ds exhibit.
ulimit -n. Increase the maximum by
Q: Does my TC400 Series card serve as a DAHDI timing device?
A: No, a TC400 Series card cannot serve as a DAHDI timing device. If
you have no other Digium cards installed which can serve as a DAHDI
Digiu m, In c . Page 31
Chapter 4: Questions and Answers
timing device, you can use the dahdi_dummy kernel mod ule to serve as
one. The dahdi_dummy kernel module can be loaded by executing
modprobe dahdi_dummy.
Where can I ask even m ore questions?
There are several places to inquire for more information about Digium
products:
1. Digium Technical Support (+1.256.428.6161) is available 7am-8pm
Central T ime, Mond ay - Friday.
2. As te ris k foru m s (forums.digium.com).
3. Asterisk users mailing list (lists.digium.com).
4. IR C ch ann el #asterisk on (irc.freenode.net).
Digium, Inc. Page 32
Appendix A Specifications
This appendix provides specifications, required environmental
conditions, and maximum power consumption for the TC400 Series
cards.
Physical.
Size: 4.69” × 2.52” × 0.63” (11.9 x 6.4 x 1.6 cm)
Weight: 2.5 oz (70.9 gm)
Interfaces.
PCI Bus (TC400B): 3.3V or 5V bus slot, half-length slot minimum
size, 33MHz minimum bus speed, compliant with PCI 2.2 or
PCB size, does not include the PCI bracket
greater.
PCI-E Bus (TCE400) - Compliant with PCI-E X1 1.0 or greater.
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
Digiu m, In c . Page 33
Appendix A: Specifications
Supported Codecs.
G.729a (8.0 Kbit)
G.723.1 (5.3 Kbit and 6.3 Kbit)
μ-law (u-law)
α-law (a-law)
Hardware an d Softw a re Requirements.
400 Mhz Pentium III or better
512 MB RAM
Available PCI or PCI-E Slot (as described previously)
Linux 2.6 kernel
Table A-1: Maximum Power Consumption
Model Power
TC400B
3.3V 0 Watts
5V 4 Watts
12V 0 Watts
TCE400
3.3V 0 Watts
5V 4 Watts
12V 5 Watts
Digium, Inc. Page 34
Appendix B Gloss ary and Acronyms
a-law
Mainly used in European telephon e networks for the conversion between
analog and digital signals in PCM applic ations. Similar to the North
American mu-law standard. Refer to G.711 on page 39 and mu-law on
page 44.
ANSI American National Standards Institute
An organizatio n which proposes and establishes standards for
international communications.
asynchronous
Not synchronized; not timed to an outside clock source. Transmission is
controlled by start bits a t the beginning and stop bits at the end of each
character. Asynchronous communications are often found in internet
access and remote office applications.
attenuation
The dissipation of a transmitted signal’s power as it travels over a wire.
bandwidth
The capacity to carry traffic. Higher bandwidth indicates the ability to
transfer more data in a given time period.
Digiu m, In c . Page 35
bit
Appendix B: Glossary and Acronyms
The smallest element of information in a digital system. A bit can be
either a zero or a one.
bps bits per second
A measurement of transmission spe ed across a data connection.
broadband
Broadband transmission sha res the bandwidth of a particular medium
(copper or fiber optic) to integrate multiple signals. The channels take up
different f requencies on the cable, integrating voic e, data, and video over
one line.
channel
A generic term for an individual dat a stre am. Ser vice providers can use
multiplexing techniques to transmit multiple channels over a common
medium.
Cat5
Category of Performance for wiring a nd cabling. Cat 5 cabling support
applications up to 100 MHz.
Cat5E
Category of Performance for wiring a nd cabling. Category 5 Enhanced
wiring supports signal r ates up to 100 MHz but adheres to stricter quality
specifications.
Digium, Inc. Page 36
Appendix B: Glossary and Acronyms
CLEC competitive local exchange carrier
A term for telephone companies established after the
T elecommunications Act of 1996 deregulated the L ECs. CLECs compete
with ILECs to offer local service. See al so LEC and ILEC.
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
T erminal equipment which is connected to the te lecommunications
network and which resides within the home or of fice of the customer . This
includes telephones, modems, terminals, routers, and television set-top
boxes.
DAHDI Digium Asterisk Hardware Device Interface
A telephony project dedicated to implementing a reasonable and
affordable compute r te lephony plat form in to t he wor ld mar ketpla ce. Al so,
the collective name for the Digium-provided drivers for Digium
telephony interface products.
DS0 Digital Signal, Level 0
A voice grade channel of 64 Kbps. The worldwide standar d speed for
digitizing voice conversation using PCM (Pulse Code Modulation).
Digium, Inc. Page 37
Appendix B: Glossary and Acronyms
DS1 Digital Signal, Level 1
1.544 Mbps in North America (T1) and Japan (J1) -up to 24 voice
channels (DS0s), 2.048 Mbps in Europe (E1) - up to 32 voice channels
(DS0s). DS1/T1/E1 lines are part of the PSTN.
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 dial ing.
E1
The European equivalent of North Ameri can T1, transmits data at 2.048
Mbps, up to 32 voice channels (DS0s).
E3
The European equival ent of North American T3, transmits data at 34.368
Mbps, up to 512 voice channels (DS0s). Equivale nt to 16 E1 lines.
EMI Electromagnetic Interference
Unwanted electrical noise present on a power line
full duplex
Data transmission in two directions simultaneously.
Digium, Inc. Page 38
FXO Fore ign Exchan ge Office
Appendix B: Glossary and Acronyms
Receives the ringing voltage from an FXS device. Outside lines are
connected to the FXO port on your TC400 Series card.
FXS Foreign Exchange Station
Initiates a nd sends ringin g vol tage. P hones ar e c onnected to t he FXS ports
on the TC400 Series card.
G.711
A recommendation by the Telecommunication Standardization Sector
(ITU-T) for an algorithm designe d to transmit and receive mulaw PCM
voice and A-law at a digita l bit rate of 64 Kbps. T his algor ithm is used fo r
digital telephone sets on digital PBX.
G.723.1
A recommendation by the Telecommunication Standardization Sector
(ITU-T) for an algorithm designe d to transmit and receive audio over
telephone lines at 6.3 Kbps or 5.3 Kbps.
G.729a
A recommendation by the Telecommunication Standardization Sector
(ITU-T) for an algorithm designe d to transmit and receive audio over
telephone lines at 8 Kbps.
H.323
A recommendation by the Telecommunication Standardization Sector
(ITU-T) for multimedia communic ations over packet-based networks.
Digium, Inc. Page 39
IAX Inter-Asterisk eXchange
Appendix B: Glossary and Acronyms
The native VoIP protocol used by Aster isk. It is an IETF standard used to
enable VoIP connections between Asterisk se rvers, and between servers
and clients that also use the IAX protoc ol.
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 c arrier
The LECs that were the or iginal carr iers in the market pr ior to th e entry of
competition and theref ore have the dominant position in the market.
interface
A point of contact between two systems, networks, or devices.
ISO International Standards Organization
LED light-emitting diode
Linux
A robust, feature-packed open source operating system based on Unix
that remains freely available on the internet. It boasts dependability and
offers a wide range of compatibility with hardware and software. Asterisk
is supported exclusively on Linux.
Digium, Inc. Page 40
loopback
Appendix B: Glossary and Acronyms
A state in which the transmit signal is reversed back as the receive signal,
typically by a far end network element.
MGCP M edia Gateway Cont rol Protocol
multiplexing
Transmitting multiple signals over a single line or channel. FDM
(frequency divisi on multiplexing) and TDM (time division multiplexi ng)
are the two most common methods. FDM separates signals by dividing
the data onto different carrier frequencies, and TDM separates signals by
interleaving bit s one after the other .
MUX multiplexer
A device which transmits multipl e signals over a single communications
line or channel. See multiplexing.
PBX private branch exchange
A smaller version of a phone company’s large central switching office.
Example: Asterisk.
PCI peripheral component interconnect
A standard bus used in most computers to connect per iphe ral devices.
POP point of presence
The physical connection poi nt between a network and a telephone
network. A POP is usually a network node serving as the equivalent of a
CO to a network service provider or an interexchange carrier.
Digium, Inc. Page 41
POTS plain old telephone service
Appendix B: Glossary and Acronyms
Standard phone service over the public switched telephone network
(PSTN). This service provides analog bandwidth of less than 4 kHz.
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 poin ts. Also r eferred to as the dial network.
QoS quality of service
A measure of telephone service, as spe cified by the Public Service
Commission.
RJ11
A six-pin ja ck typically used for connecting telephones, modems, and fa x
machines in residentia l and business settings to PBX or the local
telephone CO.
SIP Session Initiation Protocol
An IETF standard for setting up sessions be tween one or more clients. It
is currently the leading signaling protocol for Voice over IP, gradually
replacing H.323.
Digium, Inc. Page 42
T1
Appendix B: Glossary and Acronyms
A dedicated digital carrier facility which transmits up to 24 voice
channels (DS0s) and transmits data at 1.544 Mbps. Commonly used to
carry traff ic to and from priva te business networks and ISPs.
T3
A dedicated digital carrie r fa cility which consists of 28 T1 lines and
transmits data at 44.736 Mbps. Equivalent to 672 voice channels (DS0s).
TDM time division multiplexer
A device that supports simul taneous transmissi on of multiple data streams
into a single high-speed dat a stre am. TDM separa tes signals by
interleaving bit s one after the other .
telco
A generic name which refers to the telephone companies throughout the
world, including RBOCs, LECs, and PTTs.
tip and ring
The standard terminati on on the two conduct ors of a telephone circuit;
named after the physical appear a nce of the contact areas on the jack plug.
twisted pair
T wo copper wires commonly used for telephony and data
communications. The wires are wrapped loosely around each other to
minimize radio frequency interference or interference fr om other pair s in
the same bundle.
Digium, Inc. Page 43
Appendix B: Glossary and Acronyms
u-law
Also known as mu law, is the PCM quasi-logarithmic curve. It is the 64
Kbps standard North America voice amplitude sample used for
encoding/decoding.
V volts
VoIP Voice over IP
T echnology used for transmitting voice traffic over a data network using
the Internet Protoco l.
Digium, Inc. Page 44
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