Z02215
Single Chip Modem with Integrated Controller, Data Pump, and AFE
23
Table 3. AT Command Set (Continued)
Function and Description
Command
#F (cont.)
When human speech is generated at the end of the telephone connection
detecting DTMF digits, for example by a parallel voice circuit multiplexed onto
the telephone line signal, an external hybrid must be used in the telephone line
interface. This external hybrid cancels the locally generated human speech
from the received signal, improving DTMF digit detection. Without an external
hybrid, the received DTMF tones my be attenuated by the telephone network to
such low power levels that locally-generated speed prevents DTMF detection,
even when the human speech filter is used.
&G
Guard Tone The &G command selects the guard tone to be transmitted when the modem is
Options
transmitting the High band (for example, ANSWER HANDSHAKE and
ANSWER mode).
&G0
No guard tone. This value is the default value in North
America.
&G1
&G2
H0
550 Hz guard tone (V.22, V.22bis and Bell 212A only)
1800 Hz guard tone (V.22, V.22bis and Bell 212A only)
Off-hook.
H
Hook
H1
Off-hook without answering a telephone call. This option
may be disabled in countries prohibiting its use.
PS001907-0904
AT Command Set
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