Outgoing Calls - US Robotics USR3520 User Manual

Disconnect the dial-up modem from the application hardware serial port, and connect the Modemulator to
the application hardware serial port. The application hardware will now use the Modemulator for all
communications.

Outgoing Calls

In a peer-to-peer system the host Modemulator or any remote Modemulator may initiate a connection.
To initiate a connection from an originating Modemulator to an answering Modemulator, a dial
command is sent by the legacy software to the originating Modemulator. The originating Modemulator
will search its dialing directory for an entry containing the phone number from that dial command.
 If an entry for that phone number is found in the dialing directory, the originating Modemulator
will open an IP connection to the IP address of the answering Modemulator. The originating
Modemulator and the answering Modemulator will then send call-progress messages to the legacy
application software that mimic those of a dial-up modem. If the answering Modemulator is
configured to auto-answer or if the application software issues an answer command, the connection
will complete, which emulates the behavior of dial-up modems.
 If the answering Modemulator does not auto-answer or manually answer, the connection will
time-out, which emulates the behavior of dial-up modems.
 The originating Modemulator will report NO DIALTONE or BUSY or NO CARRIER if the answering
Modemulator already has a connection in-progress with another Modemulator.
 The originating Modemulator will report NOT FOUND if an entry for that phone number is not
found in the dialing directory, and a dial-up modem is not attached or not available. See
Compatibility With Dial-up Modems
Modemulator.
 If an entry for that phone number is not found in the dialing directory, and a dial-up modem is
attached and available, the originating Modemulator will forward the dial command to the
attached dial-up modem which will dial the number via the PSTN. See
Dial-up Modems
The legacy software sends the same type of command to initiate both cellular and analog connections, and
receives the same type of responses. This makes the type of connection indistinguishable and transparent
to the legacy software.
Incoming Calls
In a peer-to-peer system the host Modemulator or any remote Modemulator may answer a connection.
Incoming cellular calls will route through the answering Modemulator's Terminal port to the legacy
application software when a connection completes.
 If the answering Modemulator does not have a cellular connection already in-progress with
another Modemulator, the answering Modemulator will accept the IP connection from the
originating Modemulator. The originating Modemulator and the answering Modemulator will
Modemulator User Guide
for information about attaching a dial-up modem to a
for information about attaching a dial-up modem to a Modemulator.
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Maintain
Maintain Compatibility With