This modem can be used "out of the box", with good results.
Start by ensuring the DIP switches are in a good starting configuration. From switch one: OFF, OFF, ON, OFF, ON, OFF, OFF, ON, ON(*), OFF.
(*) Moving DIP switch #9 from OFF to ON enables command mode after typing +++. Leaving switch #9 in the OFF position (the factory default) simply causes the call to be dropped when you type +++.
After connecting to the computer, enter "ATD", and adjust the volume control (slide lever under front right corner of modem) until dial tone can be clearly heard.
at&f1 Recall factory configuration #1 att touch-tone dialing atm0 speaker turned off (M1 --> speaker on when awaiting remote answer) ats32=6 voice/data button resets modem
These notable settings are included in the f1 defaults.
atx7 extended result codes (f1 default) at&a3 Full protocol codes (f1 default) at&h1 Transmit: Hardware flow control (f1 default) at&i0 Receive: Software flow control disabled (f1 default) at&k1 compression enabled (f1 default)
A convenient cut-n-paste version:
at&f1 t m0 s32=6 &w ati4 USRobotics Courier V.Everything Settings... B0 C1 E1 F1 M0 Q0 V1 X1 BAUD=38400 PARITY=N WORDLEN=8 DIAL=TONE ON HOOK TIMER &A1 &B0 &C1 &D2 &G0 &H0 &I0 &K1 &L0 &M4 &N0 &P0 &R1 &S0 &T5 &X0 &Y1 %N6 S00=000 S01=000 S02=043 S03=013 S04=010 S05=008 S06=002 S07=060 S08=002 S09=006 S10=007 S11=070 S12=050 S13=000 S14=000 S15=000 S16=000 S17=000 S18=000 S19=000 S20=000 S21=010 S22=017 S23=019 S24=150 S25=005 S26=001 S27=000 S28=008 S29=020 S30=000 S31=000 S32=006 S33=000 S34=000 S35=000 S36=000 S37=000 S38=000 S39=000 S40=000 S41=000 S42=126 S43=200 S44=015 S45=000 S46=000 S47=000 S48=000 S49=000 S50=000 S51=000 S52=000 S53=000 S54=064 S55=000 S56=000 S57=000 LAST DIALED #: OK
On the Sun workstations running SunOS 4, the "tip dialer" command doesn't respect the hardware flow control flag in /etc/remote, and so any use of the modem to receive at high speed is likely to provoke the Sun into sending an ^S/^Q sequence. This will go to the far end of the connection and be echoed, rather than having the desired effect of slowing down the data transfer. Loss of characters is possible. The most convenient workaround for this is to have the modem power-up using ^S/^Q "software" flow control, and to have any PPP or dialer scripts switch the modem into "hardware" flow control.
A convenient cut-n-paste version:
at&f1 &h2 &i2 t m0 s32=6 &w
Then, in the chat / PPP connect mode, dial the call as:
AT &H1 &I0 DT 5551212Note that you may have to remove the spaces to prevent confusing your scripting language.
The manual states that ARQ means Automatic Repeat reQuest, a shorthand for saying that the modem connection has at least one of the possible error correction protocols enabled and operating.
The ARQ indicator on the front pannel is on while an error corrected call is in progress; the manual says that the indicator turns off briefly whenever data is being retransmitted to correct for an error.