USER’S MANUAL
Section 7: ISDN BASICS 139
CSD and CSV
Recall
that
each
ISDN
BRI
has
two
possible
B
channels.
It
is
possible
to
order
a
line
with
one
or
both
of
the
B
channels
enabled
–
and
each
may
be
enabled
for
voice
and/or
data
use.
Phone
terminology
for
the
class
of
service
is
“CSV”
for
Circuit
Switched
Voice
and
“CSD”
for
Circuit
Switched
Data.
CSV
is
for
calls
using
standard
voice
phone
service
and
allows
ISDN
to
interwork
(i.e.
to
call)
with
analog
phone
lines
and
phones.
CSD
is
required
for
Zephyr
connections
.
Even
though
you
may
be
sending
voice,
the
codec
bitstream
output
looks
like
computer
data
to
the
phone
network.
“Alternate
CSD/CSV”
or
“Alternate
voice/data”
means
both
capabilities
are
supported.
h
HOT TIP!
While the D channel is always present for signaling purposes, it can, in theory, be used for
packet data connections. ISDN lines where the D channel is used for signaling only are
sometimes referred to as “2B+0D” rather than “2B+D” service. D channel packet service is
not widely available.
Zephyr
Xstream
allows
the
option
of
a
voice
call
on
either
of
the
channels
as
well
as
the
coded
hi
‐
fi
audio.
This
capability
exists
on
both
channels.
Thus,
you
can
make
calls
to
any
normal
telephone
number
on
one
channel
while
a
program
is
being
transmitted
on
the
other.
The
Xstream
even
allows
you
to
place
two
of
these
voice
calls,
but
then,
of
course,
you
would
not
be
able
to
transmit
hi
‐
fidelity
codec
data,
since
both
channels
would
be
in
use.
Calls
from
a
Zephyr
Xport
that
is
connected
to
an
analog
"POTS"
line
also
use
CSV.
Therefore,
you
will
want
to
order
CSV
as
well
as
CSD
on
one
or
both
B
channels.
Typically,
you
would
order
an
ISDN
BRI
2B+D
line
with
alternate
CSV/CSD
on
both
channels.
If
you
don’t
need
voice
possibility
on
the
channels,
you
want
2B+D
with
only
CSD
enabled.
NT1s
The
ISDN
standard
specifies
two
reference
points,
the
‘U’
and
the
‘S’
interfaces.
The
U
is
the
single
‐
pair
bare
copper
from
the
Telco
CO.
This
is
sometimes
referred
to
as
the
“2
‐
wire”
interface.
A
device
called
a
‘Network
Termination,
Type
1’
(NT1
or
NT
‐
1)
converts
this
to
the
two
‐
pair
S
interface.
The
S
interface
sometimes
is
called
the
“4
‐
wire
interface.
The
NT1
can
also
be
generically
be
referred
to
as
NCTE
(Network
Channel
Termination
Equipment).
Outside
the
USA
&
Canada,
the
NT1
(and
NCTE
for
other
types
of
lines)
is
nearly
always
provided
by
the
telephone
company,
and
therefore
the
S
interface
must
be
on
user
equipment.
In
some
countries,
it
is
referred
to
as
a
NTBA
(Network
Termination
Basic
Access).
In
the
USA
and
Canada,
the
NT1
is
usually
provided
by
the
user.
Therefore,
the
Zephyr
Xstream
includes
both
interfaces.
The
U
interface
on
the
Zephyr
Xstream
is
on
a
2
‐
pin
6
‐
position
miniature
modular
plug
(RJ
‐
11
style).
The
S
interface
is
on
an
8
‐
pin
8
‐
position
miniature
modular
plug
(RJ
‐
45
style).
Refer
to
manual
Section
3
(Guided
Tour
of
the
Hardware)
for
additional
information
on
Zephyr
Xstream's
built
‐
in
NT1.
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...
