Some software packages, such as Dow Jones Market Manager Plus, don't appear to
get a carrier detect because the Apple Personal Modem's 0.6 seconds of carrier
detect response time is not enough time for the hookup of the software.
Carrier detect response time, register S9 on the APM, cannot be changed.
To workaround this situation, you must send a command to adjust the Carrier
Wait register, S7, to tell the modem how long to wait for a carrier. The
command is ATS7x, where x has a range of 1 to 255. For example, to reset the
default Carrier Wait, 30 seconds, send the command ATS730.