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

    <title>Configuration</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&lt;*1&gt;: ATQ0 V1 E1 -- failed with 2400 baud, next try: 9600 baud
ttyS0&lt;*1&gt;: ATQ0 V1 E1 -- failed with 9600 baud, next try: 115200 baud
ttyS0&lt;*1&gt;: ATQ0 V1 E1 -- and failed too at 115200, giving up.
Port Scan&lt;*1&gt;: S1   S2   S3   
WvModem&lt;*1&gt;: Cannot get information for serial port.
ttyACM0&lt;*1&gt;: ATQ0 V1 E1 -- OK
ttyACM0&lt;*1&gt;: ATQ0 V1 E1 Z -- OK
ttyACM0&lt;*1&gt;: ATQ0 V1 E1 S0=0 -- OK
ttyACM0&lt;*1&gt;: ATQ0 V1 E1 S0=0 &amp;C1 -- OK
ttyACM0&lt;*1&gt;: ATQ0 V1 E1 S0=0 &amp;C1 &amp;D2 -- OK
ttyACM0&lt;*1&gt;: ATQ0 V1 E1 S0=0 &amp;C1 &amp;D2 +FCLASS=0 -- OK
ttyACM0&lt;*1&gt;: Modem Identifier: ATI -- LT V.90 1.0 MT5634ZBA-USB
Data/Fax Modem (Dual Config) Version 5.18e
ttyACM0&lt;*1&gt;: Speed 4800: AT -- OK
ttyACM0&lt;*1&gt;: Speed 9600: AT -- OK
ttyACM0&lt;*1&gt;: Speed 19200: AT -- OK
ttyACM0&lt;*1&gt;: Speed 38400: AT -- OK
ttyACM0&lt;*1&gt;: Speed 57600: AT -- OK
ttyACM0&lt;*1&gt;: Speed 115200: AT -- OK
ttyACM0&lt;*1&gt;: Speed 230400: AT -- OK
ttyACM0&lt;*1&gt;: Speed 460800: AT -- OK
ttyACM0&lt;*1&gt;: Max speed is 460800; that should be safe.
ttyACM0&lt;*1&gt;: ATQ0 V1 E1 S0=0 &amp;C1 &amp;D2 +FCLASS=0 -- OK

Found an USB modem on /dev/ttyACM0.
Modem configuration written to /etc/wvdial.conf.
ttyACM0&lt;Info&gt;: Speed 460800; init "ATQ0 V1 E1 S0=0 &amp;C1 &amp;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 &amp;C1 &amp;D2 +FCLASS=0
ISDN = 0
Modem Type = USB Modem
; Phone = &lt;Target Phone Number&gt;
; Username = &lt;Your Login Name&gt;
; Password = &lt;Your Password&gt;
</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 <code>[Modem0]</code> line,
        while the <command>wvdialconf</command> command does the same
        through the <code>[Dialer Defaults]</code> 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 <code>[Modem0]</code> 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 &amp;C1 &amp;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>