<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
<code>Multi-Tech System, Inc. MT5634ZBA-USB MultiModemUSB (new
firmware)</code> 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
<code>Phone</code>, <code>Username</code> and
<code>Password</code> 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>