Comtrol AT Command Set Rev A - Manual (Page 72)

AT Commands Reference Manual
Conexant 100722B
3-46
When off-hook and either an extension is picked up or a line reversal is detected, the
modem will drop the connection. The disconnect reason in register S86=25 (this is also
defined for #UD). The user must flash the hook in order to get a dial tone due because
the remote server will be retraining.
If the local handset is picked up while the modem is off-hook, the modem will do a link-
disconnect, flash the hook for 1.5 seconds, then connect the local handset to the line. At
this point, the user dial tone should be on the local handset. The disconnect reason in
S86=25.
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.