[Asterisk-doc] Connecting to a PRI

[Gene Naden]

Since most folks are calling it T1/E1 rather than T-1/E-1, I am changing the
doc to reflect this convention.

Gene Naden
----- Original Message ----- 
From: "Stephen R. Darragh" <srd at it.net.au>
To: "Discussions regarding The Asterisk Documentation Project"
<asterisk-doc at lists.digium.com>
Sent: Wednesday, August 17, 2005 10:01 PM
Subject: Re: [Asterisk-doc] Connecting to a PRI


> Final point - it's E1 and T1, not E-1 and T-1.  Unless the dash is some
> typographic mark for you.  :)
>
> Gene Naden wrote:
> > Thansks to all for your feedback. I have incorporated the following
> > suggestions and corrections into this revised doc. Again, further
criticism
> > is welcome, it has been very helpful so far.
> >
> > 1. There is a discussion of E-1. It only lacks an example of the
zaptel.conf
> > file. The number of channels is 32
> > 2. ISDN PRI is a type of signaling used with E-1 and T-1. PRI is spelled
> > out: "Primary Rate Interface."
> > 3. "D" channels are "delta", not "data"
> > 4. Correct spelling of "confiuration"
> > 5. No longer says you cannot have PCI cards in a rack-mounted server
> > 6. No longer says the cable is RJ45
> > 7.  Zapata channels are one-indexed: Zap/1, Zap/2, etc.
> >
> > Gene Naden, MA
> > Programmer Analyst
> > GlobalTeldata II, LLC
> > 4700 N. Ravenswood
> > Chicago, IL 60640
> > (773) 878-3161 x 223
> >
> >
> > ------------------------------------------------------------------------
> >
> > T-1, E-1 AND PRI
> > 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" (delta) channel.
> >
> > ISDN PRI signaling is also used for E-1 connections. Such an E-1
> > connection has 32 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.
> >
> > 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.
> >
> > All the Digium cards for connecting to a PRI are PCI cards. 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 configuration file (zaptel.conf). It shows the
> > configuration for a single T-1 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 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 option "esf" refers to "extended super frame" and "b8zs"
refers
> > to coding "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 unless you
> > specify verbose output ("ztcfg -vv"). When you run ztcfg, 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.
> >
> > Digium says 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. Zapata channels are indexed starting at one rather than zero
> > (Zap/1, Zap/2, etc.)
> >
> >
> > ------------------------------------------------------------------------
> >
> > _______________________________________________
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> > Asterisk-Doc at lists.digium.com
> > http://lists.digium.com/mailman/listinfo/asterisk-doc
>
> -- 
> Stephen Darragh
> Technical Director
> Informed Technology
> Ph: +61 8 9380 4244  Fax: +61 8 9380 4354
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