WARNING: usually your modem—and any other "peripherals"—should be wired to your computer before you turn the computer on. This is so the computer can look for the modem and confirm that it is hooked up. Check your computer's and modem's manual for precise instructions on hooking up a modem to your computer.
If you are connecting the computer to an office phone that is part of a
Private Branch Exchange (PBX) then …
MAKING A CONNECTION
Usually you call another computer by dialing its phone number. Either you type an AT command like "ATDT 1 800 555 1212" or your software does this for you when you choose a "connect" command or something like that from a menu.
Before you get the modem's attention you need to set your software to the proper "modem settings". These settings are listed in literature about the service. As a last resort call customer service for the computer you are trying to connect to. Or else you can try different settings until you find one the lets you connect. The most common modem settings today are either 1200 or 2400 baud and "8N1", which means 8 bits, no parity, and one stop bit.
The most important settings are:
The BAUD RATE (300, 1200, and 2400 are typical low speed connections, with 2400 being the most common one for modern equipment; 9600 or 14400 are
Flow control ON or OFF (often labelled XON/XOFF). If your modem is going to talk with your computer at a faster rate than over the phone line, then flow control is essential. Be sure that your software understands that the phone line speed is different from the computer-to- modem speed. The phone line can't go any faster than 14,440 Baud. Your computer can do four times that or more.
Full or half duplex connection (LOCAL ECHO ON or OFF). In a half duplex connection the two computers take turns communicating on the same channel. This means that your computer will be the one to "ECHO" what *you* type on your screen (local echo ON), since it doesn't make sense say something, have the other computer read it, then send it back, just so you can see what you type. In a full duplex connection both computers can talk at once, so local echo is OFF.
7 or 8 bits per character. Many computer systems use the last seven bits of each byte to denote a character (up to 128 characters). The eighth bit is used for parity, flow control, or some other important signal. Nowadays 8 bits is more common.