Posted: Thu Aug 11, 2005 10:19 am Post subject: [Asterisk-doc] Connecting to a PRI
Here is my explanation of the issues involved in connecting to a PRI. I am
open to feedback, corrections, comments. This is a text file with line
breaks.
Gene Naden, MA
Programmer Analyst
GlobalTeldata II, LLC
4700 N. Ravenswood
Chicago, IL 60640
(773) 878-3161 x 223
-------------- next part --------------
WHAT IS A PRI?
A PRI is a 24-channel connection to a telephone network such as the Public
Switched Telephone Network (PSTN). PRI is a type of ISDN (Integrated
Services Digital Network) connection. A PRI can carry 23 voice channels.
The 24-th channel is used for signalling. The voice channels are referred
to as B channels and the signalling channel is referred to as the D channel.
Because a PRI uses a four-wire local loop, d4 or esf framing, and AMI or B8ZS
coding, it may also be referred to at T-1. However, T-1 can be used to carry
either voice or digital data.
You specify the type of framing and coding when you provision the PRI with the
telephone company.
CONNECTING TO A PRI
To connect to a PRI you use Zapata technology. Zapata is also used for
connecting to POTS lines (ordinary, single channel analog phone lines) and
analog phones. You configure Zapata for Asterisk in the file /etc/zaptel.conf.
Therefore this file can have information about both PRI connections and POTS
line connections. See the example below.
You do not need a Channel Service Unit/Data Service Unit (CSU/DSU) to connect
your PRI to the Asterisk computer.
The Digium cards for PRIs accept RJ45 plugs, the same type of plug used
in Category 5 cables.
All the Digium cards for connecting to a PRI are PCI cards. Therefore, you
cannot use a 1U rack-mounted server if you are connecting to a PRI. The TE405P
card is an example of a PRI interface card. It has four ports and therefore
can connect to up to four PRIs. Alternatively, one or more ports could be
connected to channel banks for analog phones. However, channel banks are
beyond the scope of this discussion.
Below is a sample Zapata configuraion file (zaptel.conf). It shows the
configuration for a single PRI, two analog phones and two POTS lines.
The line "fxols=1-23" reflects the fact that the connection is to a PRI
rather than a channel bank. "ls" refers to "loop start."
The way the channel numbering works is that the first 96 channels (one
through 96) are for the TE405P card. The fxo and fxs channels, if any,
must follow, rather than precede, the PRI channels. In other words,
you cannot have fxoks=1-2, fxsks=3-4, bchan=5-27, dchan=28. If you
do this you will get an obscure error message.
Regarding the line beginning with the word "span", there is one span
for each port that is in use. The "span" line has the following format:
span=port number, timing, line build out, framing, coding
The port number is one because the PRI is connected to the first port on the
card.
The timing should be 1 for one of the ports. The line connected to that
port provides a timing reference. If other ports are used, the timing for those
ports should be two or zero. Two means this line is a secondary timing reference
and zero means this line is not used as a timing reference.
Line build out reflects the length of last leg of the connection and is set to
zero if the length is less than 133 feet. The specific values for line build
out are specified in the sample zaptel.conf that comes with Asterisk.
The framing and coding are discussed in "WHAT IS A PRI", above. The option "esf"
refers to "extended super frame" and "b8zs" refers to "Bipolar with 8 Zero
Substitution."
TROUBLE-SHOOTING
When the PRI card was purchased from Digium, Digium has provided free
technical support for configuring the card.
The lights on the PRI card can be red, amber/green or green. When all is
well they are green.
If Asterisk aborts when you try to start it, there are several things you
can check:
The Linux modules for your Zapata cards have to be loaded in order for the
connections to work. You load the PRI driver, wct4xxp, before you load the
FXS/FXO driver, wctdm.
You also have to execute the program ztcfg to get things to work. If all is
well, when you run ztcfg it should not produce any output. When you
do this, the lights should change to green, even if Asterisk has not been
started.
Loading of the modules may or may not be done automatically by the system.
It is possible to construct a loop-back plug to test your PRI card.
You do this using an RJ45 plug, connecting pin one to pin four and pin
two to pin five. When the loop-back connector is connected to the card, the
light should turn green. Again, the modules have to be loaded and possibly
ztcfg has to have been run.
The B channels listed in zaptel.conf must agree with the channels listed in
/etc/asterisk/zapata.conf, otherwise Asterisk may abort when you try to
start it.
Posted: Thu Aug 11, 2005 12:07 pm Post subject: [Asterisk-doc] Connecting to a PRI
Gene,
Thanks very kindly for your manuscript! I will do some work editing it,
and send my changes to you for your review and correction. Leif and
Jared may contribute as well (that's how we work).
Once we are all pleased with the final version, we will determine how to
incorporate it into the existing work.
Again, thanks for the contribution! This is very valuable.
Here is my explanation of the issues involved in connecting
to a PRI. I am open to feedback, corrections, comments. This
is a text file with line breaks.
Gene Naden, MA
Programmer Analyst
GlobalTeldata II, LLC
4700 N. Ravenswood
Chicago, IL 60640
(773) 878-3161 x 223
--
No virus found in this outgoing message.
Checked by AVG Anti-Virus.
Version: 7.0.338 / Virus Database: 267.10.5/68 - Release Date:
10/08/2005
Posted: Thu Aug 11, 2005 12:23 pm Post subject: [Asterisk-doc] Connecting to a PRI
Gene Naden wrote:
Quote:
Here is my explanation of the issues involved in connecting to a PRI. I am
open to feedback, corrections, comments. This is a text file with line
breaks.
Gene Naden, MA
Programmer Analyst
GlobalTeldata II, LLC
4700 N. Ravenswood
Chicago, IL 60640
(773) 878-3161 x 223
Posted: Thu Aug 11, 2005 12:55 pm Post subject: [Asterisk-doc] Connecting to a PRI
Comments inline:
Many thanks for taking the time to doc this.
Julian.
Gene Naden wrote:
Quote:
Here is my explanation of the issues involved in connecting to a PRI. I am
open to feedback, corrections, comments. This is a text file with line
breaks.
Gene Naden, MA
Programmer Analyst
GlobalTeldata II, LLC
4700 N. Ravenswood
Chicago, IL 60640
(773) 878-3161 x 223
A PRI is a 24-channel connection to a telephone network such as the Public
Switched Telephone Network (PSTN). PRI is a type of ISDN (Integrated
Services Digital Network) connection. A PRI can carry 23 voice channels.
The 24-th channel is used for signalling. The voice channels are referred
to as B channels and the signalling channel is referred to as the D channel.
Euro ISDN PRI have 31 channels, 16th used for signalling
Quote:
Because a PRI uses a four-wire local loop, d4 or esf framing, and AMI or B8ZS
coding, it may also be referred to at T-1. However, T-1 can be used to carry
either voice or digital data.
or E1 for euroisdn
Quote:
You specify the type of framing and coding when you provision the PRI with the
telephone company.
CONNECTING TO A PRI
To connect to a PRI you use Zapata technology. Zapata is also used for
connecting to POTS lines (ordinary, single channel analog phone lines) and
analog phones. You configure Zapata for Asterisk in the file /etc/zaptel.conf.
Therefore this file can have information about both PRI connections and POTS
line connections. See the example below.
You do not need a Channel Service Unit/Data Service Unit (CSU/DSU) to connect
your PRI to the Asterisk computer.
The Digium cards for PRIs accept RJ45 plugs, the same type of plug used
in Category 5 cables.
All the Digium cards for connecting to a PRI are PCI cards. Therefore, you
cannot use a 1U rack-mounted server if you are connecting to a PRI. The TE405P
Um, we are - most 1U servers have riser boards allowing for the card to
be mounted sideways. Both our TE405p and TE405P are in 1U servers.
Quote:
card is an example of a PRI interface card. It has four ports and therefore
can connect to up to four PRIs. Alternatively, one or more ports could be
connected to channel banks for analog phones. However, channel banks are
beyond the scope of this discussion.
Below is a sample Zapata configuraion file (zaptel.conf). It shows the
configuration for a single PRI, two analog phones and two POTS lines.
The line "fxols=1-23" reflects the fact that the connection is to a PRI
rather than a channel bank. "ls" refers to "loop start."
The way the channel numbering works is that the first 96 channels (one
through 96) are for the TE405P card. The fxo and fxs channels, if any,
must follow, rather than precede, the PRI channels. In other words,
you cannot have fxoks=1-2, fxsks=3-4, bchan=5-27, dchan=28. If you
do this you will get an obscure error message.
Regarding the line beginning with the word "span", there is one span
for each port that is in use. The "span" line has the following format:
span=port number, timing, line build out, framing, coding
The port number is one because the PRI is connected to the first port on the
card.
The timing should be 1 for one of the ports. The line connected to that
port provides a timing reference. If other ports are used, the timing for those
ports should be two or zero. Two means this line is a secondary timing reference
and zero means this line is not used as a timing reference.
Line build out reflects the length of last leg of the connection and is set to
zero if the length is less than 133 feet. The specific values for line build
out are specified in the sample zaptel.conf that comes with Asterisk.
The framing and coding are discussed in "WHAT IS A PRI", above. The option "esf"
refers to "extended super frame" and "b8zs" refers to "Bipolar with 8 Zero
Substitution."
TROUBLE-SHOOTING
When the PRI card was purchased from Digium, Digium has provided free
technical support for configuring the card.
The lights on the PRI card can be red, amber/green or green. When all is
well they are green.
If Asterisk aborts when you try to start it, there are several things you
can check:
The Linux modules for your Zapata cards have to be loaded in order for the
connections to work. You load the PRI driver, wct4xxp, before you load the
FXS/FXO driver, wctdm.
You also have to execute the program ztcfg to get things to work. If all is
well, when you run ztcfg it should not produce any output. When you
do this, the lights should change to green, even if Asterisk has not been
started.
Loading of the modules may or may not be done automatically by the system.
It is possible to construct a loop-back plug to test your PRI card.
You do this using an RJ45 plug, connecting pin one to pin four and pin
two to pin five. When the loop-back connector is connected to the card, the
light should turn green. Again, the modules have to be loaded and possibly
ztcfg has to have been run.
The B channels listed in zaptel.conf must agree with the channels listed in
/etc/asterisk/zapata.conf, otherwise Asterisk may abort when you try to
start it.
Posted: Thu Aug 11, 2005 1:41 pm Post subject: [Asterisk-doc] Connecting to a PRI
OK
----- Original Message -----
From: "Jim Van Meggelen" <jim@vanmeggelen.ca>
To: "'Discussions regarding The Asterisk Documentation Project'"
<asterisk-doc@lists.digium.com>
Sent: Thursday, August 11, 2005 3:11 PM
Subject: RE: [Asterisk-doc] Connecting to a PRI
Quote:
Gene,
Thanks very kindly for your manuscript! I will do some work editing it,
and send my changes to you for your review and correction. Leif and
Jared may contribute as well (that's how we work).
Once we are all pleased with the final version, we will determine how to
incorporate it into the existing work.
Again, thanks for the contribution! This is very valuable.
asterisk-doc-bounces@lists.digium.com wrote:
> Here is my explanation of the issues involved in connecting
> to a PRI. I am open to feedback, corrections, comments. This
> is a text file with line breaks.
>
> Gene Naden, MA
> Programmer Analyst
> GlobalTeldata II, LLC
> 4700 N. Ravenswood
> Chicago, IL 60640
> (773) 878-3161 x 223
--
No virus found in this outgoing message.
Checked by AVG Anti-Virus.
Version: 7.0.338 / Virus Database: 267.10.5/68 - Release Date:
10/08/2005
Posted: Thu Aug 11, 2005 1:42 pm Post subject: [Asterisk-doc] Connecting to a PRI
Thank you for reading my doc and thanks for the corrections. :)
----- Original Message -----
From: "Mats Karlsson" <mats.o.karlsson@gmail.com>
To: "Discussions regarding The Asterisk Documentation Project"
<asterisk-doc@lists.digium.com>
Sent: Thursday, August 11, 2005 3:23 PM
Subject: Re: [Asterisk-doc] Connecting to a PRI
Quote:
Gene Naden wrote:
> Here is my explanation of the issues involved in connecting to a PRI. I
am
Quote:
> open to feedback, corrections, comments. This is a text file with line
> breaks.
>
> Gene Naden, MA
> Programmer Analyst
> GlobalTeldata II, LLC
> 4700 N. Ravenswood
> Chicago, IL 60640
> (773) 878-3161 x 223
>
>
> ------------------------------------------------------------------------
>
> _______________________________________________
> Asterisk-Doc mailing list
> Asterisk-Doc@lists.digium.com
> http://lists.digium.com/mailman/listinfo/asterisk-doc
Nice work Gene,
But maybe you could correct the :
A PRI is a 24-channel
to
A PRI is a multi channel
And then correct the text in the document to reflect that PRI can be
either T1 or E1 and that T1 is 24 channels and E1 is 30 channels.
And it is RJ48C that is used for connecting T1/E1's, the pinout differs
to RJ45's but its the same type of 8 pin connector.
Posted: Thu Aug 11, 2005 2:37 pm Post subject: [Asterisk-doc] Connecting to a PRI
Julian,
Thanks for your comments.
----- Original Message -----
From: "Julian Lyndon-Smith" <asterisk@dotr.com>
To: "Discussions regarding The Asterisk Documentation Project"
<asterisk-doc@lists.digium.com>
Sent: Thursday, August 11, 2005 3:25 PM
Subject: Re: [Asterisk-doc] Connecting to a PRI
Quote:
Comments inline:
Many thanks for taking the time to doc this.
Julian.
Gene Naden wrote:
> Here is my explanation of the issues involved in connecting to a PRI. I
am
Quote:
> open to feedback, corrections, comments. This is a text file with line
> breaks.
>
> Gene Naden, MA
> Programmer Analyst
> GlobalTeldata II, LLC
> 4700 N. Ravenswood
> Chicago, IL 60640
> (773) 878-3161 x 223
>
>
> ------------------------------------------------------------------------
>
> WHAT IS A PRI?
>
> A PRI is a 24-channel connection to a telephone network such as the
Public
Quote:
> Switched Telephone Network (PSTN). PRI is a type of ISDN (Integrated
> Services Digital Network) connection. A PRI can carry 23 voice channels.
> The 24-th channel is used for signalling. The voice channels are
referred
Quote:
> to as B channels and the signalling channel is referred to as the D
channel.
Quote:
Euro ISDN PRI have 31 channels, 16th used for signalling
>
> Because a PRI uses a four-wire local loop, d4 or esf framing, and AMI or
B8ZS
Quote:
> coding, it may also be referred to at T-1. However, T-1 can be used to
carry
Quote:
> either voice or digital data.
or E1 for euroisdn
>
> You specify the type of framing and coding when you provision the PRI
with the
Quote:
> telephone company.
>
> CONNECTING TO A PRI
>
> To connect to a PRI you use Zapata technology. Zapata is also used for
> connecting to POTS lines (ordinary, single channel analog phone lines)
and
Quote:
> analog phones. You configure Zapata for Asterisk in the file
/etc/zaptel.conf.
Quote:
> Therefore this file can have information about both PRI connections and
POTS
Quote:
> line connections. See the example below.
>
> You do not need a Channel Service Unit/Data Service Unit (CSU/DSU) to
connect
Quote:
> your PRI to the Asterisk computer.
>
> The Digium cards for PRIs accept RJ45 plugs, the same type of plug used
> in Category 5 cables.
>
> All the Digium cards for connecting to a PRI are PCI cards. Therefore,
you
Quote:
> cannot use a 1U rack-mounted server if you are connecting to a PRI. The
TE405P
Quote:
Um, we are - most 1U servers have riser boards allowing for the card to
be mounted sideways. Both our TE405p and TE405P are in 1U servers.
> card is an example of a PRI interface card. It has four ports and
therefore
Quote:
> can connect to up to four PRIs. Alternatively, one or more ports could
be
Quote:
> connected to channel banks for analog phones. However, channel banks are
> beyond the scope of this discussion.
>
> Below is a sample Zapata configuraion file (zaptel.conf). It shows the
> configuration for a single PRI, two analog phones and two POTS lines.
>
> # zaptel.conf
>
> loadzone = us
>
> #te405p card
> span=1,1,0,esf,b8zs
> bchan=1-23
> dchan=24
> fxols=1-23
>
> #tdm400 card
> fxoks=97-98
> fxsks=99-100
>
> The 23 B channels and the D channel are shown.
>
> The line "fxols=1-23" reflects the fact that the connection is to a PRI
> rather than a channel bank. "ls" refers to "loop start."
>
> The way the channel numbering works is that the first 96 channels (one
> through 96) are for the TE405P card. The fxo and fxs channels, if any,
> must follow, rather than precede, the PRI channels. In other words,
> you cannot have fxoks=1-2, fxsks=3-4, bchan=5-27, dchan=28. If you
> do this you will get an obscure error message.
>
> Regarding the line beginning with the word "span", there is one span
> for each port that is in use. The "span" line has the following format:
>
> span=port number, timing, line build out, framing, coding
>
> The port number is one because the PRI is connected to the first port on
the
Quote:
> card.
>
> The timing should be 1 for one of the ports. The line connected to that
> port provides a timing reference. If other ports are used, the timing
for those
Quote:
> ports should be two or zero. Two means this line is a secondary timing
reference
Quote:
> and zero means this line is not used as a timing reference.
>
> Line build out reflects the length of last leg of the connection and is
set to
Quote:
> zero if the length is less than 133 feet. The specific values for line
build
Quote:
> out are specified in the sample zaptel.conf that comes with Asterisk.
>
> The framing and coding are discussed in "WHAT IS A PRI", above. The
option "esf"
Quote:
> refers to "extended super frame" and "b8zs" refers to "Bipolar with 8
Zero
Quote:
> Substitution."
>
> TROUBLE-SHOOTING
> When the PRI card was purchased from Digium, Digium has provided free
> technical support for configuring the card.
>
> The lights on the PRI card can be red, amber/green or green. When all is
> well they are green.
>
> If Asterisk aborts when you try to start it, there are several things
you
Quote:
> can check:
>
> The Linux modules for your Zapata cards have to be loaded in order for
the
Quote:
> connections to work. You load the PRI driver, wct4xxp, before you load
the
Quote:
> FXS/FXO driver, wctdm.
>
> You also have to execute the program ztcfg to get things to work. If all
is
Quote:
> well, when you run ztcfg it should not produce any output. When you
> do this, the lights should change to green, even if Asterisk has not
been
Quote:
> started.
>
> Loading of the modules may or may not be done automatically by the
system.
Quote:
>
> It is possible to construct a loop-back plug to test your PRI card.
> You do this using an RJ45 plug, connecting pin one to pin four and pin
> two to pin five. When the loop-back connector is connected to the card,
the
Quote:
> light should turn green. Again, the modules have to be loaded and
possibly
Quote:
> ztcfg has to have been run.
>
> The B channels listed in zaptel.conf must agree with the channels listed
in
Quote:
> /etc/asterisk/zapata.conf, otherwise Asterisk may abort when you try to
> start it.
>
>
> ------------------------------------------------------------------------
>
> _______________________________________________
> Asterisk-Doc mailing list
> Asterisk-Doc@lists.digium.com
> http://lists.digium.com/mailman/listinfo/asterisk-doc
Posted: Thu Aug 11, 2005 3:58 pm Post subject: [Asterisk-doc] Connecting to a PRI
Julian Lyndon-Smith wrote:
Quote:
Euro ISDN PRI have 31 channels, 16th used for signalling
Noop, I disagree, its 30 channels for payload.
A "raw" E1 (aka. G.703) is 2.048 Mbps = 32 x 64000 bps = 32
TimeSlots/Channels.
And a framed E1 (aka. G.704+G.732, Structured G.703, 30B+D) has 30
channels for transporting and 2 for signaling/sync.
Time slot zero (TS0) is used for synchronization and TS16 is used for
signaling.
It is possible to use 31 channels but I have never seen that in use for
voice purpose but it's quite common in datacom.
Posted: Thu Aug 11, 2005 5:28 pm Post subject: [Asterisk-doc] Connecting to a PRI
Gene Naden wrote:
Quote:
Here is my explanation of the issues involved in connecting to a PRI. I am
open to feedback, corrections, comments. This is a text file with line
breaks.
Gene Naden, MA
Programmer Analyst
GlobalTeldata II, LLC
4700 N. Ravenswood
Chicago, IL 60640
(773) 878-3161 x 223
A PRI is a 24-channel connection to a telephone network such as the Public
Switched Telephone Network (PSTN). PRI is a type of ISDN (Integrated
Services Digital Network) connection. A PRI can carry 23 voice channels.
The 24-th channel is used for signalling. The voice channels are referred
to as B channels and the signalling channel is referred to as the D channel.
Because a PRI uses a four-wire local loop, d4 or esf framing, and AMI or B8ZS
coding, it may also be referred to at T-1. However, T-1 can be used to carry
either voice or digital data.
As other people have pointed out, T1s are North American. The generic
term DS1 is probably best here--a DS1 can be an E1, T1, J1, etc.
Basically any type of DS1 circuit can be provisioned PRI. Also, the
underlying circuit _IS_ a T1 (or whichever); the distinction between
types of T1s is in the provisioning and protocols used on the line.
Finally, a T1 circuit can also cary be provisioned to carry both voice
and data and the same time.
Posted: Fri Aug 12, 2005 8:29 am Post subject: [Asterisk-doc] Connecting to a PRI
On Friday, August 12, 2005, 11:54:36, Jim Van Meggelen wrote:
Quote:
asterisk-doc-bounces@lists.digium.com wrote:
> On Thursday, August 11, 2005, 21:28:18, Nick Bachmann wrote:
>>> ...
>> As other people have pointed out, T1s are North American. The
>> generic term DS1 is probably best here--a DS1 can be an E1,
>> T1, J1, etc.
>
> Isn't E1 32 DS0's whereas DS1 is 24 DS0's?
E1 is 32 DS0s, T1 is 24 DS0s,
A DS1 is a trunking facility which is composed of DS0s. In some parts of
the world, a DS1 will be 32 Channels, in others, A DS1 will be 24
channels. This inconsistency is probably why the term DS1 is so rarely
used - it begs the question: E1 or T1?
As this thread is illustrating there's a need to distinguish between
transmission rates (DS0, DS1, E1, DS3, etc.) and the carrier technology
used (T1, T3, etc.)
--
rodd@polylogics.com Usenet is like a herd of performing elephants
Rod Dorman with diarrhea; massive, difficult to redirect,
awe-inspiring, entertaining, and a source of
mind-boggling amounts of excrement when you
least expect it. -- Gene Spafford
On Thursday, August 11, 2005, 21:28:18, Nick Bachmann wrote:
>> ...
> As other people have pointed out, T1s are North American. The
> generic term DS1 is probably best here--a DS1 can be an E1,
> T1, J1, etc.
Isn't E1 32 DS0's whereas DS1 is 24 DS0's?
E1 is 32 DS0s, T1 is 24 DS0s,
A DS1 is a trunking facility which is composed of DS0s. In some parts of
the world, a DS1 will be 32 Channels, in others, A DS1 will be 24
channels. This inconsistency is probably why the term DS1 is so rarely
used - it begs the question: E1 or T1?
Posted: Fri Aug 12, 2005 2:20 pm Post subject: [Asterisk-doc] Connecting to a PRI
I am reading all the discussion on this. It may take me a few days to sort
it all out even with all the help I am getting.
----- Original Message -----
From: "Jim Van Meggelen" <jim@vanmeggelen.ca>
To: "'Rod Dorman'" <rodd@polylogics.com>; "'Discussions regarding The
Asterisk Documentation Project'" <asterisk-doc@lists.digium.com>
Sent: Friday, August 12, 2005 10:54 AM
Subject: RE: [Asterisk-doc] Connecting to a PRI
Quote:
asterisk-doc-bounces@lists.digium.com wrote:
> On Thursday, August 11, 2005, 21:28:18, Nick Bachmann wrote:
>>> ...
>> As other people have pointed out, T1s are North American. The
>> generic term DS1 is probably best here--a DS1 can be an E1,
>> T1, J1, etc.
>
> Isn't E1 32 DS0's whereas DS1 is 24 DS0's?
E1 is 32 DS0s, T1 is 24 DS0s,
A DS1 is a trunking facility which is composed of DS0s. In some parts of
the world, a DS1 will be 32 Channels, in others, A DS1 will be 24
channels. This inconsistency is probably why the term DS1 is so rarely
used - it begs the question: E1 or T1?
Posted: Tue Aug 16, 2005 12:33 pm Post subject: [Asterisk-doc] Connecting to a PRI
My earlier writing omitted mention of E-1. I have written a few paragraphs
to try to remedy it. Would the interested persons please have a look at it
and criticize, especially
folks familiar with E1.
Gene Naden, MA
Programmer Analyst
GlobalTeldata II, LLC
4700 N. Ravenswood
Chicago, IL 60640
(773) 878-3161 x 223
-------------- next part --------------
T-1 AND E-1
In the context of Asterisk, T-1 and E-1 are digital telephony schemes
that multiplex a number of voice channels onto one line. E-1 is used
mainly in Europe and Asia, while T-1 is used in the United States and
Canada. In either case, signaling and framing information must be
carried, either within the voice channels or in separate, non-voice
channels. There are various signallng and framing schemes.
One signaling scheme that is used with Asterisk for T-1 connections
is ISDN PRI (Integrated Services Digital Network, Primary
Rate Interface.) With IDSN PRI, a T-1 connection has 24 channels.
In the context of Asterisk, channels 1-23 carry voice and are referred
to as "B" (bearer) channels. Channel 24 carries signaling information
and is referred to as a "D" (data) channel.
ISDN PRI signaling is also used for E-1 connections. Such an E-1
connection has 31 channels. For Asterisk, channels 1-15 and 17-31 carry
voice and are called "B" channels, while channel 16 carries signaling
information and is called the "D" channel. Channel zero is used for
framing.
Posted: Tue Aug 16, 2005 1:09 pm Post subject: [Asterisk-doc] Connecting to a PRI
Hi!
On Tue, 2005-08-16 at 15:36 -0500, Gene Naden wrote:
Quote:
My earlier writing omitted mention of E-1. I have written a few paragraphs
to try to remedy it. Would the interested persons please have a look at it
and criticize, especially folks familiar with E1.
I can't comment on E1, but one slight correction on PRI channelization
terminology: the "D" designation of the signalling channel stands for
"delta", not "data". The same applies for the 16Kbps "D" channel used
in BRI.
I just joined the list, so I must have missed the balance of your
writing. I would love to peruse, is it in CVS?
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