Modems let you link your computer to the outside world. Connected properly, you can use a modem to send data and files to anyone else with a modem and a computer. You can also access information and download it for use on your PC.

This chapter explains what a modem is, and how to set one up for use with your PC. In addition, you learn about using a modem as a fax machine and how to troubleshoot modem problems.

A modem is a hardware device that lets two computers exchange information over telephone lines. Using a modem, you can connect directly to another computer that is also equipped with a modem, to an online service provider such as America Online, or to the Internet and World Wide Web. When you're connected, you can send and receive files or communicate in real time--which means you communicate with little or no delay, as if you were face-to-face with the person at the other computer.

Modems let you communicate over standard telephone lines with other com- puter users. You can transfer data, exchange electronic files, and even carry on a typed conversation in real time.

These days, a modem is a vital part of a PC; without one, you'll miss out on a wide range of opportunities. Here's a small sampling of things you can do with a modem:

The word modem is actually an abbreviation of the terms modulator-demodulator, which describe how a modem works.

Here are the basic steps involved in transferring data using modems:

1. Software in your computer activates the modem, which listens on the phone line for a dial tone, then dials a specified number.

2. The receiving modem on the other end answers the call and sends out a signal which the sending modem recognizes, establishing a connection.

3. The modem sending information converts the computer's digital signals into analog signals that can be sent over the phone lines (this is called modulating).

4. The receiving modem translates the incoming data back into digital signals that its computer can understand (this is called demodulating).

5. When the online session is over, the computers issue a command telling the modems to hang up.

In order to make a connection using a modem, you need the following:

Choosing a modem is not as difficult as choosing some other computer components because there is less variety. There are two basic types of modems:

An external modem has controls and status lights on the front that you can use to monitor transmissions.

NOTE: You can attach a telephone to either kind of modem so when you are not using the modem, you can use the phone to make regular calls.

Aside from choosing an internal or external modem, the other main factors to consider are:

NOTE: If you only use your modem to send and receive e-mail messages, you may be able to get by with a modem as slow as 14.4Kbps. If you use your modem to transmit and download files, or if you like to surf the World Wide Web--which uses a lot of graphics images--you should purchase the fastest modem available.

NOTE: The communications parameters set for the sending modem must match the communications parameters set for the receiving modem.

Modems also operate under communications parameters. Modem communications parameters include:

One final consideration when purchasing a modem is whether or not you want fax capabilities. Because most modems currently available include fax capabilities, it's not much of a decision. Fax modems generally don't cost any more than standard modems, so in addition to using the modem to communicate with other computers, you can use it to communicate with facsimile machines.

With a fax modem, you can:

NOTE: If you already have a stand-alone fax machine, you do not have to use the fax options on the modem. The device will work fine as a plain modem.

To use the fax capabilities, you need to have specific fax software or data communications software that includes fax support.

Connecting a modem involves attaching the modem device to your PC and to the telephone line. The modem should come with the necessary equipment, including a standard RJ-11 telephone cord. The steps you take depend on whether you have an internal modem or an external modem.

If you have an internal modem, you must install it by removing the cover of the system unit and plugging the modem card into a vacant expansion slot. Unless you are extremely confident about working inside your computer, you should have the modem installed by a professional computer technician.

If you have an external modem, however, you can easily connect it yourself. To connect an external modem to your PC, follow these steps:

1. Locate the serial cable that came with the modem. It should have a 25-pin male connector at one end and a 25-hole female connector at the other end.

2. Plug the female connector into an open 25-pin serial port on the PC's system unit, and plug the male connector into the modem device.

3. Secure the connectors using the screws on either side.

4. Locate the power cord for the modem device and plug it into an electrical wall socket, power strip, or uninterruptible power supply.

After the modem is connected to your PC, you must connect it to the phone line. This procedure is the same for both external and internal devices.

To connect a modem to the phone line, follow these steps:

1. Locate the two phone jacks on the modem, labeled Phone and Line. They will be on the outside of an external modem, or on the back of the system unit if you have an internal modem. They look just like the phone jacks on your telephone.

2. Plug one end of a standard RJ-11 telephone cord (it should come with the modem) into the Line jack, and the other end into the wall jack for your telephone.

3. Plug one end of another RJ-11 telephone cord into the Phone jack, and the other end into your telephone.

TIP: If you have a phone line dedicated for use with your computer, you do not need to connect the modem to the telephone. You only need to connect to a phone if you want to be able to use the phone for regular calls when the modem is not in use.

An internal modem is integrated into your PC; you will interact with it using your data communications software. If you have an external modem, however, you can control and monitor certain functions on the device itself. For example, status lights on the front of the modem let you know whether the modem is on, and whether it is in send mode, ready to dial and transmit data, or receive mode, ready to answer and download data.

If you look at the front of your external modem, these are some of the controls you are likely to find:

Be sure to read the documentation that comes with your modem for complete instructions on understanding the modem controls and status lights.

Windows 95 uses the Install New Modem Wizard to help you identify and set up newly installed modems. Before starting the wizard, it helps to know the manufacturer and model of the modem. Also, if you have an external modem, make sure it is turned on.

To use the Install New Modem Wizard, follow these steps:

1. Double-click My Computer and then double-click the Control Panel folder icon. Alternatively, click the Start button, then open the Settings menu and click Control Panel.

2. Double-click the Modems icon in the Control Panel folder to open the Modems Properties dialog box. Click the Add button to start the Install New Modem Wizard, then choose Next.

3. Windows 95 immediately tries to detect and identify the modem. When it does, it displays the Verify Modem screen of the wizard, displaying the name or type of modem that it finds. It also identifies the communications port where the modem is connected. If the information is correct, choose Next, then choose Finish.

4. If Windows 95 cannot detect the modem, the wizard displays a screen where you can select the modem information yourself. (You can display the same screen by clicking the Change button if the information on the Verify Modem screen of the wizard is incorrect.) Select the modem's manufacturer in the Manufacturers list box. Select the specific modem in the Models list box, then choose OK.

NOTE: If your modem is not on the list, choose the Standard Modem Types manufacturer and select the model according to speed. Or, click the Have Disk button and follow the instructions to install a vendor-supplied driver.

5. Choose Next, then choose Finish. Windows 95 installs the necessary drivers for the modem, then closes the wizard. Choose Close to close the Modems Properties dialog box.

On the Verify Modem page of Windows 95's Install New Modem Wizard, you see the port and modem type Windows has detected. Click C hange to select a different modem.

NOTE: If Windows 95 detects the new device when you first turn on your PC, it will prompt you to run the Add New Hardware Wizard to detect it and set it up. Go ahead and use the Add New Hardware Wizard; it performs the same function as the Install New Modem Wizard, but will detect and set up other types of hardware devices as well.

When a modem doesn't work, there could be problems with the hardware, the communications software, or the software settings. Here are a few tips for locating the problem and fixing it.

If your external modem is not working, here are a few things to check:

If your modem dials, but doesn't connect, here are a few things to check:

If your modem doesn't get a dial tone, here are some things to check:

If Windows or your communications software displays a message telling you that it can't find your modem, here are some things to check: