<sect1 id="configurations-ppp-modem-config">

    <title>Configuring Modem Device</title>

    <para>

        Once the modem hardware has been installed in the computer, it

        is necessary to determine what device location the operating

        system assigned to it, so applications like

        <application>chat</application> be able to know which device

        to talk to.  This configuration process can be realized

        through the <command>wvdialconf</command> command, distributed

        with the <package>wvdial</package> package.

    </para>

    <para>

        Another way to configure modems installed in your computer is

        through the graphical interface provided by

        <command>system-config-network</command> command. This

        interface may result specially useful when you need to

        configure your computer to establish Modem connections to

        remote Internet Service Providers (ISPs).  The interface

        provided by <command>system-config-network</command> command

        uses the same configuration file that

        <command>wvdialconf</command> command does (e.g.,

        <filename>/etc/wvdial.conf</filename>), however, there are

        some differences in the way these commands create

        configuration files that we need to be aware of.

    </para>

    <para>

        This section describes how you could use the

        <command>wvdialconf</command> and

        <command>system-config-network</command> commands to configure

        the modem installed in your computer, as well as possible

        issues you might face if these two commands are arbitrarily

        combined one another.

    </para>

    <sect2 id="configurations-ppp-modem-config-wvdial">

    <title>The <command>wvdialconf</command> Command</title>

    <para>

        The <command>wvdialconf</command> automatically detects the

        location the operating system assigned to your modem, its

        maximum baud rate, a good initialization string for it, and

        generates/updates the <command>wvdial</command> configuration

        file (<filename>/etc/wvdial.conf</filename>) the

        <command>wvdial</command> command needs to work. To set the

        modem configuration through <command>wvdialconf</command>

        command, run the command as follows:

    </para>

    <screen>sudo /usr/bin/wvdialconf /etc/wvdial.conf</screen>

    <para>

        This command will produce an output like the following:

    </para>

<screen>

Scanning your serial ports for a modem.

ttyS0<*1>: ATQ0 V1 E1 -- failed with 2400 baud, next try: 9600 baud

ttyS0<*1>: ATQ0 V1 E1 -- failed with 9600 baud, next try: 115200 baud

ttyS0<*1>: ATQ0 V1 E1 -- and failed too at 115200, giving up.

Port Scan<*1>: S1   S2   S3   

WvModem<*1>: Cannot get information for serial port.

ttyACM0<*1>: ATQ0 V1 E1 -- OK

ttyACM0<*1>: ATQ0 V1 E1 Z -- OK

ttyACM0<*1>: ATQ0 V1 E1 S0=0 -- OK

ttyACM0<*1>: ATQ0 V1 E1 S0=0 &C1 -- OK

ttyACM0<*1>: ATQ0 V1 E1 S0=0 &C1 &D2 -- OK

ttyACM0<*1>: ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0 -- OK

ttyACM0<*1>: Modem Identifier: ATI -- LT V.90 1.0 MT5634ZBA-USB

Data/Fax Modem (Dual Config) Version 5.18e

ttyACM0<*1>: Speed 4800: AT -- OK

ttyACM0<*1>: Speed 9600: AT -- OK

ttyACM0<*1>: Speed 19200: AT -- OK

ttyACM0<*1>: Speed 38400: AT -- OK

ttyACM0<*1>: Speed 57600: AT -- OK

ttyACM0<*1>: Speed 115200: AT -- OK

ttyACM0<*1>: Speed 230400: AT -- OK

ttyACM0<*1>: Speed 460800: AT -- OK

ttyACM0<*1>: Max speed is 460800; that should be safe.

ttyACM0<*1>: ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0 -- OK

Found an USB modem on /dev/ttyACM0.

Modem configuration written to /etc/wvdial.conf.

ttyACM0<Info>: Speed 460800; init "ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0"

</screen>

    <para>

        and a <command>wvdial</command> configuration file like the

        following:

    </para>

<screen>

[Dialer Defaults]

Modem = /dev/ttyACM0

Baud = 460800

Init1 = ATZ

Init2 = ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0

ISDN = 0

Modem Type = USB Modem

; Phone = <Target Phone Number>

; Username = <Your Login Name>

; Password = <Your Password>

</screen>

    <note>

    <para>

        It is possible to configure the same computer to act both as

        server (i.e., to receive incoming calls from clients) and

        client (i.e., to realize outgoing calls to servers). However,

        be aware that only one of these connections can be established

        at a time.

    </para>

    </note>

    </sect2>

    <sect2 id="configuration-ppp-modem-config-scn">

    <title>The <command>system-config-network</command> Command</title>

    <para>

        The interface provided by

        <command>system-config-network</command> command doesn't

        detect the configuration intially created by

        <command>wvdialconf</command> command. In fact, if you set a

        new (modem) hardware configuration through it, any

        configuration previously created by

        <command>wvdailconf</command> command will be lost. On the

        other hand, if you firstly generate the configuration file

        using the interface provided by

        <command>system-config-network</command> command and later run

        the <command>wvdialconf</command> command over it, you will

        end up having two similar configuration settings under

        different definitions stored in the same configuration file.

    </para>

    <note>

    <para>

        The <command>wvdial</command> command doesn't understand the

        configuration file produced by

        <command>system-config-network</command> command, even both

        <command>wvdialconf</command> and

        <command>system-config-network</command> commands use the same

        configuration syntax to create the configuration file.

    </para>

    </note>

    <para>

        Inside the <filename>/etc/wvdial.conf</filename> configuration

        file, the interface provided by

        <command>system-config-network</command> identifies default

        modem configurations through the [Modem0] line,

        while the <command>wvdialconf</command> command does the same

        through the [Dialer Defaults] line. Something

        interesting about the configuration file created by

        <command>system-config-network</command> is that it is

        possible to create several ISP configurations that reuse

        default settings in the [Modem0] section. For

        example, consider the following example:

    </para>

<screen>

[Modem0]

Modem = /dev/ttyACM0

Baud = 460800

SetVolume = 2

Dial Command = ATDT

Init1 = ATZ

Init3 = ATM1L2

FlowControl = CRTSCTS

[Dialer Vispa_Internet]

Username = signup

Password = rebel

Phone = 08453080125

Stupid Mode = 1

Init1 = ATZ

Init2 = ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0

Inherits = Modem0

</screen>

    <caution>

    <para>

        The interface provided by

        <command>system-config-network</command> command doesn't

        provide modem detection (as <command>wvdialconf</command>

        command would do) and uses the <filename>/dev/modem</filename>

        as default location. This location doesn't exists by default,

        so whatever configuration you set from it will not work. To

        solve this issue, chose one of the following workarounds: 

    </para>

    <itemizedlist>

    <listitem>

    <para>

        Replace the <filename>/dev/modem</filename> location by that

        one <command>wvdialconf</command> found when the interface

        provided by <command>system-config-network</command> ask you

        to enter the modem device.

    </para>

    </listitem>

    <listitem>

    <para>

        Create <filename>/dev/modem</filename> location as a symbolic

        link to that location found by <command>wvdialconf</command>

        command. For example:

        <screen>sudo /bin/ln -s /dev/ttyACM0 /dev/modem</screen>

    </para>

    </listitem>

    </itemizedlist>

    </caution>

    </sect2>

</sect1>