USER’S MANUAL
Section 7: ISDN BASICS 134
With
the
digital
nature
of
the
modern
telephone
network
is
hidden
from
subscribers,
voice
and
signaling
has
been
delivered
just
as
they
have
been
since
the
era
of
wooden
phone
sets
and
mechanical
bells.
In
the
age
of
digital
communication,
this
“last
mile”
bottleneck
has
become
increasingly
frustrating
for
those
who
have
need
to
send
digital
information
through
Ms.
Bell’s
wires.
With
most
of
the
network
now
digital,
it
is
clearly
odd
that
we
have
been
using
modems
to
convert
digital
information
to
analog
beeps
just
to
accommodate
the
mile
or
two
of
ancient
analog
linkage
at
each
end
of
a
thousand
‐
mile
long
digital
connection.
ISDN
is
the
technology
which
has
evolved
to
eliminate
this
analog
bottleneck
yet
still
utilize
existing
copper
infrastructure.
It
is
currently
the
only
technology
that
allows
fully
digital
access
to
the
Public
Switched
Telephone
Network.
7.2
The ISDN Basic Rate Interface (BRI)
On
one
ISDN
BRI
circuit,
there
are
three
simultaneous
channels:
Two
64kbps
“bearer”
channels
for
the
transmission
of
user
information
and
one
16kbps
signaling
channel
for
call
set
‐
up
and
status
communication.
This
is
Basic
Rate
Interface
(BRI),
2B+D
service.
In
Europe
and
other
countries
it
is
also
referred
to
as
ISDN
‐
2
or
SØ.
It
can
be
implemented
over
most
of
the
millions
of
standard
copper
two
‐
wire
phone
circuits
already
in
service.
?
CURIOSITY NOTE!
While the D channel is always present for signaling, it can, in theory, be used for connections
to the public packet network. ISDN lines where the D channel is used only for signaling are
sometimes referred to as 2B+0D rather than 2B+D service. D channel packet service is not
widely available and is not used by Zephyr Xstream.
ISDN
BRIs
are
perfectly
matched
to
Zephyr
Xstream’s
transmission
capabilities.
One
channel
provides
high
quality
mono,
while
the
two
channels
can
carry
near
‐
CD
quality
stereo.
i
ISDN TIP!
In some cases, your ISDN line, while having 2 B channels, will only have only one phone
number. This is the case of the AT&T Custom PTP protocol, and may be the case with ETS
300 (Euro-ISDN) and INS 64 (Japanese ISDN). This does not generally present a problem.
This works as if the lines are assigned to a short “hunt group” i.e.; the first incoming call
will be assigned to Line 1, and the second incoming call will be assigned to Line 2. Of course
you have the option of which line to use on outgoing calls.
Summary of Contents for Zephyr Xstream
Page 2: ......
Page 26: ...USER S MANUAL Section 1 QUICK RESULTS 14...
Page 30: ...USER S MANUAL Section 2 INTRODUCTION Getting to Know the Zephyr Xstream 18...
Page 70: ...USER S MANUAL Section 3 GUIDED TOUR of the HARDWARE 58...
Page 144: ...USER S MANUAL Section 6 AUDIO CODING REFERENCE 132...
Page 164: ...USER S MANUAL Section 8 LIVEWIRETM IP Audio 152...
Page 310: ...USER S MANUAL Appendix 1 Codec Interoperability Information 298...
Page 320: ...USER S MANUAL Appendix 3 ISDN Cause Phrases Values 308...
Page 324: ...USER S MANUAL Appendix 4 Known Working SPID Formats by Telco 312...
Page 356: ...USER S MANUAL Appendix 9 Modular Cable Guide 344...
