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Operation
Call Control Basics
Call control involves call initiation, completing a connection, call answering, and disconnecting a
call. The following paragraphs describe the procedures required for each type of call control.
The modem can be commanded to initiate a call in any of three ways:
•
Manually, using a telephone number supplied at the time the call is initiated
•
Manually, using a telephone number stored previously in one of the 10 memory cells provided
for that purpose
•
Automatically in response to an Off-to-On transition of the DTR interface circuit, using a
telephone number stored previously in memory cell 0.
Table 3-2
Common Call Control Commands
Command
AT
AT D
P
(follows D
command)
T
(follows D
command)
W
(part of dial
command)
;
(part of dial
command)
Sn
(following D
command)
R
(last character in
dial command)
AT A
AT H
060R122-000
Issue 15
This will...
get the attention of the modem, in
that a command is to follow.
get the modem to dial the specified
telephone number that follows.
tell the modem to pulse dial.
tell the modem to tone dial.
tell the modem to wait for a dial
tone before dialing the number that
follows.
cause the modem to return to the
command mode, rather than go to
data mode) after it has dialed the
number.
tell the modem to dial a previously
stored number.
cause the modem to establish a
call in answer mode to an
originate-only modem.
force the modem to answer
incoming call. (Used for manually
answering a call.)
force the modem to hang up.
SpectraComm Dual V.34 Modem
Installation and Operation
Call Control Basics
Remember...
this command must always precede any
command line, except A/.
your number can contain up to 30 digits.
use dial digits 0 - 9
use dial digits 0-9 and symbols A B C D # *
use this command when you have to dial 9 to
obtain an outside line.
this separates a command string containing
more than 30 characters (avoids buffer
overflow).
you can store 10 telephone numbers
(n = 0 - 9) up to 30 digits each.
the R command must be the last character in the
dial string before you enter a carriage return.
the modem does not wait for a ring; no matter
what is specified in the S0 register
you must first be in command mode.
3-3
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