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

    <title>The Modem Device</title>

    <para>

        This section describes the steps you should follow to install

        and configure the modem device in the computer. This section

        applies both to server and client computers.

    </para>

    <sect2 id="configurations-ppp-modem-installation">

    <title>Installation</title>

    <para>

        The modem device installation consists on attacthing the modem

        hardware both to the computer and the telephone line. To

        connect the modem to your computer, you need to connect the

        serial or USB cable that comes from the modem hardware to the

        appropriate input on your computer. To connect the modem to

        the telephone line system, you need to unplug the cable that

        connects your phone device and plug it on the modem device,

        specifically in the port reserved for data transmission.

        Later, using a similar cable, you could connect your phone

        device to the modem's phone port, so you be able of realizing

        phone calls when no data transmition take place, as well.

    </para>

    <para>

        To be on the safe side, do all the installation with the

        computer turned off. Then, when everthing has been put in

        place, turn it on. Once the system is up, you can verify the

        modem hardware using either the <command>lsusb</command> or

        <command>lspci</command> commands. For example, if you are

        using an USB modem like that one we mentioned before, run the

        following command:

    </para>

    <screen>sudo /sbin/lsusb</screen>

    <para>

        and you should get an output similar to the following:

    </para>

<screen>

Bus 003 Device 001: ID 0000:0000  

Bus 001 Device 001: ID 0000:0000  

Bus 001 Device 002: ID 058f:6366 Alcor Micro Corp. Multi Flash Reader

Bus 002 Device 001: ID 0000:0000  

Bus 005 Device 003: ID 06e0:f104 Multi-Tech Systems, Inc.

MT5634ZBA-USB MultiModemUSB (new firmware)

Bus 005 Device 001: ID 0000:0000  

Bus 005 Device 002: ID 046d:c018 Logitech, Inc. Optical Wheel Mouse

Bus 004 Device 001: ID 0000:0000 

</screen>

    <para>

        The relevant line here is that mentioning the existence of a

        Multi-Tech System, Inc. MT5634ZBA-USB MultiModemUSB (new

        firmware) device.

    </para>

    </sect2>

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

    <title>Configuration</title>

    <para>

        The modem configuration depends on whether you are setting the

        server computer or the client computer. Nevertheless, the

        configuration stuff related to modem detection is both valid

        on server acn client computers.

    </para>

    <sect3 id="configurations-ppp-modem-config-detect">

    <title>Detecting The Modem Device</title>

    <para>

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

        is necessary to determine what device inside the operating

        system it was assigned to, so applications like

        <command>pppd</command> and <command>chat</command> can talk

        to it. To perform this very specific configuration step, run

        the following command:

    </para>

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

    <para>

        The <command>wvdialconf</command> command comes with the

        <package>wvdial</package><footnote>

        <para>

            <command>wvdial</command> is an intelligent PPP dialer

            that takes care of dialing a modem and starting PPP to

            connect almost any ISP without special configurations. It

            is something like the <application>chat</application>

            program, except that it uses heuristics to guess how to

            dial and log into your server rather than forcing you to

            write a login script.

        </para></footnote> package and detects your modem, its maximum

        baud rate, and a good initialization string. Later, using this

        information, it generates or updates the

        <command>wvdial</command> configuration file

        (<filename>/etc/wvdial.conf</filename>).  The output produced

        by <command>wvdialconf</command> command looks as 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>

        which produces the following <command>wvdial</command>

        configuration file:

    </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>

    <para>

        At this point, the computer should be ready to attend incoming

        calls.  When an incoming call is detected by the computer, the

        <application>pppd</application> deamon responds to it. To

        configure the way such incoming calls are attended (e.g.,

        forcing user authentication, restricting the phone numbers the

        calls can be initiated from, etc.), you need to set-up the

        <application>pppd</application> deamon to fit your needs. On

        the other hand, if you are configuring a computer to act as

        client, you need to realize a few more tunning steps on

        <filename>/etc/wvdial.conf</filename> to set the information

        related of that Internet Service Provider (ISP) you want to

        get connected in (e.g., by uncommenting the

        Phone, Username and

        Password lines above to set the appropiate values

        there) and then, instruct to <application>pppd</application>

        deamon about the user credential (e.g., user name and

        password) you will use to connect the target ISP. In this

        case, credentials defined both in

        <application>wvdial</application> and

        <application>pppd</application> applications must be exactly

        the same.

    </para>

    </sect3>

    <sect3 id="configurations-ppp-modem-config-server">

    <title>The Server Settings</title>

    <para>

        ...

    </para>

    </sect3>

    <sect3 id="configurations-ppp-modem-config-client">

    <title>The Client Settings</title>

    <para>

        ...

    </para>

    </sect3>

    </sect2>

    <sect2 id="configurations-ppp-modem-verification">

    <title>Verification</title>

    <para>

    ...

    </para>

<screen>

--> WvDial: Internet dialer version 1.54.0

--> Cannot get information for serial port.

--> Initializing modem.

--> Sending: ATZ

ATZ

OK

--> Sending: ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0

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

OK

--> Modem initialized.

--> Sending: ATDT520347

--> Waiting for carrier.

ATDT520347

NO DIALTONE

--> No dial tone.

--> Disconnecting at Thu Sep 29 13:04:30 2011

</screen>

    </sect2>

</sect1>