<sect1 id="connectivity-dialup-overview">

    <title>Overview</title>

    <para>

        This manual describes the configuration of two computers, one

        acting as server and other as client. The server computer (see

        <xref linkend="connectivity-dialup-server" />) will be

        configured to provide internet services and the client

        computer (see <xref linkend="connectivity-dialup-client" />)

        to make use of those internet services. The connection medium

        used by both client and server computer is the telelphone line

        (i.e., the same medium you use to realize telephone calls).

        In this configuration, both client and server computers use

        special devices named <quote>Modems</quote> to transmit data

        in form of sound across the telephone line (see 

        linkend="connectivity-dialup-modem" />).

    </para>

    <para>

        This infrastructure is made available to you free of charge,

        however, you should know that maintaining it might cost you

        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>

        To use this infrastructure, people connecting from the client

        computers to the server computer must agree the conditions

        described in <xref linkend="connectivity-dialup-policy" />.

    </para>

    <para>

        It is worth to mention that, you can configure one computer to

        act both as server and client. In this case, your computer

        acts as client of another server computer, not the one you

        have configured in the same computer of your client (i.e., you

        cannot call yourself and expect to answer any incoming call

        using the same line you used to make the outgoing call, it

        doesn't make any sense).  Likewise, your server will act as

        server for another client computer, not the one you have

        configured. In resume, you can both receive incoming calls or

        realize outgoing calls using the same telephone line, but only

        when the telephone line is free from any incoming or outgoing

        call.

    </para>

    <para>

        This infrastructure could result very useful to you when you

        want to share IP packages with your friends and the only

        communication medium you and your friends have access to is a

        telephone network.

    </para>

</sect1>