Specifications

MultiModem ISI Hybrid Series, ISIHI-2S/2U 75
Chapter 4—MODEM AT Commands, S-Registers, Result Codes
&Qn Asynchronous Communications Mode
n = 0, 5, or 6
Default: &Q5
Allows you to select the type of asynchronous communications mode for your modem.
Note: These commands are the same as several of the \Nn commands, described later in
this chapter.
&Q0 selects asynchronous mode with data buffering. This is the same as \N0, nonerror
correction mode with data buffering.
&Q5 selects error control with data buffering. This is the same as \N3, V.42/MNP auto-
reliable mode.
&Q6 selects asynchronous mode with data buffering. This is the same as \N0, non-error
correction mode with data buffering.
Online Connection Commands
The following commands control the conditions of the online connection.
Bn Answer Tone
n = 0, 1, 2, 3, 15, or 16
Default: B1 and B16
Selects the frequency the modem uses for its answer tone. (The answer tone is the tone
transmitted by the receiving modem to the calling modem, thus initiating the handshake
between the two modems.) At higher speeds (2400bps and above) there is no conflict
because all protocols use the Bell frequency of 2225Hz. Lower speeds require different
frequencies.
B0 selects ITU-T V.22 mode when the modem is at 1200bps.
B1 selects Bell 212A when the modem is at 1200bps. This is a default.
B15 selects V.21 when the modem is at 300bps.
B16 selects Bell 103J when the modem is at 300bps. This is a default.
Cn Dummy Command
-Cn Data Calling Tone
n = 0 or 1
Default: -C0
The data calling tone is a tone of a certain frequency and cadence, as specified in the V.25
standards, which identifies whether it is remote data, fax, or voice. The frequency is
1300Hz, with a cadence of .5s on and 2s off.
-C0 disables the V.25 data calling tone.
-C1 enables the V.25 data calling tone.