I am getting disconnected frequently. What causes this?

Disconnects
Disconnects can be one of the most frustrating problems you can encounter while online. Infrequent disconnects (once a month or so) are just a part of being on the Internet. Frequent disconects can frazzle your nerves. Please remember that if you are having connection problems, it is our desire to help you solve them. However, there are a mulititude of things that can cause disconnects and troubleshooting can take some time and lots of patience.

If they occur often, here's a check list:

Phone Line Noise
While voice communication and faxes can handle the occasional hum, static or line cross-over, any of those can cause your modem connection to belly-up. Your modem is trying to turn that noise into readable data, and when it can't, you're likely to get one of those "windows is unable to negotiate a compatible set of protocol" messages. Or one of "the computer you are dialing is not answering at this time."
The first step is to take a phone connected to the data line you are using (if it is separate from your voice line), check for dial-tone and then punch in just one number in order to break the dial-tone. Any sound, other than complete silence can cause connection problems. If you detect any noise, it's time for a call to your telephone service provider.

Premises Wiring/Fax Software
Faulty wiring, bad phone jacks and plugs, cheap phones, old/antique phones, phone line splitters, too many phones or other devices can cause problems. Disconnect everything from the phone line (fax machines, answering machines,etc), keep the phone line at least three inches away from electrical cords, extension cords, printer cables, etc. Inductance from electrical lines and radio transmitters wreaks havoc with phone lines.
Fax software will sometimes "take control" of the modem when you try to use the modem to access the Internet. Disabling the fax software during your Internet online time will clear up this interference. When you are through with your Internet session, you can re-enable your fax software.

Weather Changes
Temperature changes and wet/dry fluctuations can result in connection problems. Changes in temperature can cause changes in the phone cables (expansion, retraction), altering the quality of the line temporarily. If you normally maintain connection but suddenly have problems after a recent rainstorm, it is probably a result of water on/in the lines resulting in hum, static and cross talk.

Excessive Retraining
Modem retrains during the session (this is not the same as "speed-shifting," the normal fallback and forward changes of data transfer speed.) Retraining is a process by which two connected modems keep adjusting without disconnecting. It is the same thing that occurs in the first few seconds when the two connecting modems are trying to "handshake." This procedure can be initiated by either modem when unsatisfactory signal reception is detected and no data is transferred. The intended result is to improve the receiver's signal processing by decreasing the data rate (poor data signal quality) or by increasing the data rate (good data signal quality). Most modem manufacturers have designed their modems to disconnect after 12 retrain sequences.

Incorrect speed setting
Your modem speed is set incorrectly. Here is a short list of settings. 14.4 Modem---Set speed to 19200 28.8 Modem---Set speed to 38400 or 57600 33.6 Modem---Set speed to 57600
Don't set your 33.6 to 115200 in Windows. It just can't handle it well.

Call Waiting
Call waiting must be disabled in your configuration settings if you don't want to be disconnected when you are online and a second call comes in. This can be done by placing a "*70," (without the quotes) in front of the dial-in number.

Thunderstorms
Not only should you not be online during thunderstorms, but your line jack should be disconnected. Power surges can come through the phone line and destroy your modem. While it might function well enough to send faxes, the modem's ability to make and maintain an Internet connection can be affected by a the power surge.

Multiple logins
Individual dial-up accounts are allowed only one login at a time. If one of your family members is accessing the account from home, while you try to access it from the office, the system will disconnect the second connection.