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'3. Command sets
&D Data Terminal Ready (DTR)
+D
Commands: &DO, &D1, &D2, &D3
Used to determine function of the V.24 signal DTR (Data
Terminal Ready)/108.2.
A typical application is to use DTR to disconnect the modem.
The modem ignores DTR.
cace.-|
The modem returns to command state when
_y/
{detecting an ON to OFF transition on DTR.
The modem hangs up, returns to command
esgic.
state and disables autoanswer when detecting
"Jan ON to OFF transition on DTR.
Autoanswer can be reenabled by turning DTR
"LON.
' | The modem assumes initialisation state if il
- | detects an ON to OFF transition on DTR
The command i is used in asynchronous mode only.
"See also the +&A command.
1300 Hz Call Tone
Commands: +D0, +D1
The Cail Tone is a signal, defined in ITU-T V.25, which is used
to inform the telephone network that the call was placed by an
automatic dial unit.
If you know in advance that an originating modem sends a 1300
Hz call tone, you will obtain a quicker call detection by using the
AT command
+D. In some cases it may be necessary to turn it
off, especially for modems including the V.23 standard.
As the 1300 Hz Call Tone is only a recommendation and not
required for modems with auto dialler, you cannot expect to
always receive it.
=.
{Not active
2
Active. The modem sends a 1300 Hz call! tone
Giving the command +B1, causes the answering modem to
search for a 1300 Hz call tone to decide if this is an automatic
modem call, or a voice (or a manual modem) call.
LZTR104006 R1.00
3-13
Zat 14.4/14.4-7 and Zat 19.2/19.2-7
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