88
ISDN TA/V
V.25bis is an ITU communication standard which defines a means of
initiating communications synchronously or asynchronously over a PSTN
or ISDN line.
V.25bis provides an alternative method of originating and answering calls
when the communication environment calls for it. For example, when the
ISDN TA/V has been configured for V.25bis operation, you use the
commands supported by this standard to dial an ISDN number (similar to
using the AT command
D
), store numbers (similar to the AT command
&Z
n
=x
), or dial the number stored (similar to the AT command dial modifier
DS=
n
).
The following chapter discusses those V.25bis commands supported by your
ISDN TA/V, and the response to those commands.
18.1 Call Request Commands
Call request commands are issued from the DTE to the ISDN TA/V and are
responsible for initiating any dial calls. Call request commands include call
request with number provided (
CRN
), and call request with stored memory
address provided (
CRS
).
18.1.1 C
ALL
R
EQUEST WITH
N
UMBER
P
ROVIDED
(CRN)
The
CRN
command dials the ISDN number entered from the DTE. CRN is
similar to the
ATD
command. The CRN command format is:
CRN
n
Where
n
is the ISDN number to be dialed.
18.1.2 C
ALL
R
EQUEST WITH
S
TORED
M
EMORY
A
DDRESS
P
ROVIDED
(CRS)
The
CRS
command dials the ISDN number stored in the request directory
location. CRS is similar to the
ATDS
command. The CRS command is:
CRS
x
Where
x
is directory location 1-20.
The ISDN TA/V responds to the command with either a
VAL
(valid) or
INV
(invalid) response followed by a call progress report such as connect (
CNX
)
or failure (
CFI
).
18. V.25bis Dialing Commands
