<sect1 id="server-usage-overview">

    <title>Overview</title>

    <para>

        The infrastructure described in this chapter uses the

        client/server model to provide a public mail service through

        the telephone line. In this configuration, we (the poeple

        building the infrastructure) provide the information you (the

        person using the infrastructure) need to know in order to

        establish a dial-up connection from the client computer to the

        server computer through the telephone line.

    </para>

    <para>

        The infrastructure described in this chapter is made available

        to you free of charge, however, you should know that

        maintaining it costs both money and time. For example, for

        each hour the server computer is on production there is an

        electrical consume that need to be paid every month.

        Likewise, each call that you establish from the client

        computer to the server computer will cost you money, based on

        the location you made the call from and the time you spend

        connected.

    </para>

    <para>

        In this manual, by dial-up connection we mean the action of

        dialing-up a server computer from a client computer through a

        Modem attached to the telephone line. In this infrastructure,

        dial-up connections are always established from the client

        computer to the server computer and never the other way

        around.  The main purpose of a client computer to establish a

        dial-up connection with the server computer will be using one

        or more Internet services provided in the server computer.

    </para>

    <para>

        In order for the server computer to answer telephone calls, it

        is required to install a Modem device in it (see 

        linkend="server-install-hardware" />). Once the Modem device

        has been installed, you need to install and configure both

        <application>mgetty</application> and

        <application>pppd</application> programs.  The

        <application>mgetty</application> program must be run by

        <systemitem class="daemon">init</systemitem> daemon in order

        to take control over the Modem device. By default, inside

        &TC;; (release 5.5), mgetty isn't configured to start with

        <systemitem class="daemon">init</systemitem> daemon so you

        need to do it yourself (see ...). Later, for attending

        connection requests, you need to configure mgetty to use the

        <application>pppd</application> program, so the Point-to-Point

        Protocol (PPP) can be talked and IP packages can be

        interchanged between the client computer and the server

        computer. Later, you need to configure

        <application>pppd</application> to adjust it to your needs

        (see ...). 

    </para>

    <para>

        Once you've configured both <application>mgetty</application>

        and <application>pppd</application> programs, the server

        computer should be ready to attend incoming calls.  The

        remaining of this chapter describes the way incoming calls are

        attended by the server computer once they have arrived to its

        Modem device.

    </para>

</sect1>