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. 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. 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 lsusb or lspci commands. For example, if you are using an USB modem like that one we mentioned before, run the following command: sudo /sbin/lsusb and you should get an output similar to the following: 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 The relevant line here is that mentioning the existence of a Multi-Tech System, Inc. MT5634ZBA-USB MultiModemUSB (new firmware) device. 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. 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 pppd and chat can talk to it. To perform this very specific configuration step, run the following command: sudo /usr/bin/wvdialconf /etc/wvdial.conf The wvdialconf command comes with the wvdial wvdial 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 chat 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. package and detects your modem, its maximum baud rate, and a good initialization string. Later, using this information, it generates or updates the wvdial configuration file (/etc/wvdial.conf). The output produced by wvdialconf command looks as the following: 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" which produces the following wvdial configuration file: [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> At this point, the computer should be ready to attend incoming calls. When an incoming call is detected by the computer, the pppd 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 pppd 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 /etc/wvdial.conf 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 pppd 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 wvdial and pppd applications must be exactly the same. ... ... ... --> 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