Comtrol AT Commands for SmartACFL - Manual (Page 54)

Command Reference Manual
3-34 Conexant 100722A
Behavior in Voice Mode (+FCLASS=8)
When in voice mode and an extension is picked-up, a <DLE>P is sent to the DTE. When the modem is off-hook , a line
reversal may also be detected in which case a <DLE>l is sent to the DTE.
In voice mode, there is no blocking of ATDT when the line is in use. Also, there is no automatic hang-up in voice mode as in
data mode. There is only the above stated <DLE> shielding event reporting.
Operation in Data Mode
Line-In-Use (Enabled by AT-STE=1, AT-STE=3, AT-STE=5, or AT-STE=7)
Case 1: Telephone Line is in Use
If an ATDT, ATDP or ATDL is issued while Line-In-Use detection is enabled and the telephone line is in use, the modem will
immediately return the message LINE-IN-USE to the DTE without going off-hook, and then return to command mode.
Case 2: Telephone Line is in Use But Disconnected
If an ATDT, ATDP or ATDL is issued while Line-In-Use detection is enabled and the telephone line is NOT in use, the modem
will go off-hook after a short pause, then respond with CONNECT or NO CARRIER message.
Case 3: Telephone Line is Not Connected to Modem
If an ATDT, ATDP or ATDL is issued while Line-In-Use detection is enabled and the telephone line is not connected, the
modem will go off-hook momentarily, go back on-hook, then respond with NO DIAL TONE message.
Extension Pick-up (Enabled by AT-STE=2, AT-STE=3, AT-STE=6, or AT-STE=7):
Case 1: Modem off-hook, Local Handset Goes Off-Hook
If the local handset goes off-hook while the modem is in a data connection, the local handset will be muted. The modem will
then send a GSTN Cleardown to the remote modem and then go on-hook. The modem will then send a NO CARRIER
message to the DTE. A result code of 25 will be left in S86 register. After 2 seconds, the local handset will be connected to
the telephone line so the user hears the dial tone.
Case 2: Modem off-hook, Extension Pick-up
If the modem is connected and another extension goes off-hook, the modem will send a GSTN Cleardown to the remote
modem and then immediately hang-up. Due to the noise possibly being added to the line when a telephone extension is
picked-up, a GSTN Cleardown may or may not successfully be received by the remote mode. If the GSTN Cleardown is not
received successfully by the remote modem, the remote modem may attempt a retrain until the retrain fails and the remote
modem drops the line. In any case, the modem will send a NO CARRIER message to the DTE immediately after sending the
GSTN Cleardown. A result code of 25 will be left in the S86 register.
Because the extension is off-hook, the modem cannot flash the hook for the central office to generate a dial tone. In this
case, the user must flash the extension handset to obtain a dial tone.
Remote Hang-up (enabled by AT-STE=4, AT-STE=5, AT-STE=6, or AT-STE=7):
Case 1: Modem off-hook, Remote Hang-up
If the modem is connected (off-hook) and the remote modem/server goes hangs up, the central office may issue a line
polarity reversal. If a line polarity reversal is detected, the modem will drop the call and respond with NO CARRIER. The
reason for hang-up can be determined by #UD or by S86=25. A line reversal can also be simulated by simply pulling out the
telephone line during a connection.