If you have a standard configuration of a modem connected to a 25 pin
serial port, the factory defaults are usually fine.  Occasionally if you
have non standard cables or serial interface or a modem that does not
recognise Australian dial tone, then you will need to modify through the
init strings how the modem will work with the software/hardware of the
serial port.   Usually it is a matter of fine tuning the operation of the
modem e.g. when you dial nationally, S7=30 is typically ok, but on an
international call, particularly if 1 or more satellite hops are involved
then extending the S7 value (BTW this is the wait time for carrier) to 45
or more will usually give a better chance of establishing comms on dodgy
circuits.  As I said if you are mainly using your modem in Australia with
standard equipment then you will not have to fine tune very much.   Some of
the commands merely echo back to the user information (type atw1 when
before dialling your number and the modem will return info such as line
speed, error correction used and DTE speed - helpful but not necessary

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