Internet Connection Types - Dial-up Modem

The oldest method available to access the Internet is the dial-up modem. This method is still in use in areas that don’t have access to broadband technologies and by people who prefer a low-cost method of connecting to the Internet.

The dial-up modem uses standard telephone lines by converting the digital signal from the workstation to an analog signal, then sending the analog signal across the telephone lines to the ISP. The ISP converts the analog signal it receives back to a digital signal for processing on the server, which then forwards it to the Internet.

The dial-up modem uses the telephone line the same way a telephone does, so when you’re using your dial-up modem to connect to the Internet, your phone line is busy and can’t accept incoming calls. It’s also not a good idea to pick up another telephone on the same line while the dial-up modem is operating.

Two basic types of dial-up modems are available:
• External modems
• Internal modems

External modems are separate from the workstation and connect to it with a USB cable or a serial cable. Serial cables are bulky, multi-pin cables that plug into the serial ports on the workstation, usually labeled COM1 or COM2. This is an old technology, and many newer workstations don’t provide COM1 or COM2 ports. Therefore, it’s difficult these days to find external modems that use serial port connections. USB external modems plug into the standard USB port on the workstation and communicate as a normal USB device.

Ubuntu can usually automatically detect an externally connected modem, whether it’s a serial or USB connection. If Ubuntu doesn’t automatically detect your external modem, first check to make sure the modem turned on when you boot your system. If it did, then check to make sure the cable is secured to the proper port on the workstation.

Internal modems are built inside the workstation. Some workstation motherboards contain modems built into them, while others use cards you can plug directly into the motherboard. Ubuntu has somewhat of a checkered past in dealing with internal modems. If Ubuntu automatically detects your internal modem, you’re in good shape. If it doesn’t, you may have to invest in an external modem instead.

The download speed of dial-up modems is limited to 56 kilobits per second (kbps). Unfortunately, this speed rate is not often achieved because the actual transmission speed of a connection depends on the clarity of the analog signal, which for many telephone lines isn’t all that great. What may be annoying static on your phone line when you talk is death to a modem connection!

There’s a special type of internal modem, called Winmodem, that may cause problems for you. Winmodems perform some of the functionality of a modem in software that (as the name suggests) runs on the Windows platform. You must be careful about Winmodems because not all of them can be used by Linux. The best resource for working with Winmodems in Linux is the linmodems.org web site: http://linmodems.org. This site provides detailed advice on which Winmodems are directly supported in Linux and how to obtain drivers for those that aren’t.

Source of Information : Wiley Ubuntu Linux Secrets