The Macintosh Portable Data Modem 2400 doesn't have an option for answering in
originate mode, but it can be tricked into doing this. It won't be quite as
convenient as setting up a single register, though, and you may want to use a
script to automate it, depending on the communications program you are using.
Scenario
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Because the goal is to make the modem answer in originate mode, and the modem
doesn't have this option, we're going to dial in originate mode, instead and
just not dial a number. The trick is to set the modem options to disable Dial
Tone detection. If this isn't done, the modem will wait for a dial tone when
the other end is sending a carrier.
Follow these steps:
1) Set the modem's active response codes with: ATX3
(Enables OK, RING, NO CARRIER, ERROR, BUSY, and CONNECT messages, but
disables dial tone detection which would prevent this from working.)
2) Dial the host and do the necessary steps to generate a callback.
3) Wait for Macintosh Portable modem to generate RING.
4) Immediately force the modem off-hook with: ATD
(The Macintosh Portable modem should wait for carrier and negotiate with the
host's modem for a connection.)
5) When the CONNECT message appears, the modems will be talking.
This could easily be put into a communications program script, simplifying
the process.