Configure modem to ignore DTR and assert DCD

Remote Serial Console HOWTO
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# C.3. Configure modem to ignore DTR and assert DCD

The computer reboots a few times during the upgrade. These reboots hang up the modem. Having to dial in a number of times during the upgrade can become annoying. Altering the modem's configuration to ignore Data Terminal Ready will cause the modem not to hang up when the computer is rebooted. To ignore DTR send the command AT&D0 to the modem.

We may also wish to disconnect during the install to reduce transmission charges. Configuring the modem to hold Data Carrier Detect on will prevent any disconnection and reconnection from being apparent to the installer. Use the command AT&C0 to always hold DCD high.

Apply these changes using the procedure in Section 12.3, retaining all of the other `AT` commands.

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