Cause: There are too many causes to be listed here.
Solution #1: Modem Strings
Some modem manuals recommend that you add special modem initialisation (or ‘init’) strings to your modem settings. These are a series of numeric commands that can improve efficiency and stability of online connections. Check your modem documentation or Web site for more information.
Solution #2: Modem Drivers
Modem manufacturers continually tweak and refine their modem software. Re-installing the software of your modem or running a firmware upgrade may significantly improve connectivity and speed. Most manufacturers make copies of their latest software available for download on their Web sites.
Solution #3: Software Modems
Some modems use the processing power of your computer to perform some tasks. If you own a software modem and an older PC, or a PC with low memory, this may affect your connection speed. Also, having a lot of applications open while using a software modem may affect the speed and stability of your connection.
Solution #4: Modem Port Speeds
External modems connect to your computer via a communications port to a piece of hardware known as a ‘serial card’. Although on all new PCs, these are built into the motherboard, some older PCs, however, have slower serial cards, which struggle to keep up with faster modems. If you use a 56K modem in conjunction with an older PC, you may experience unstable connections. We suggest you consult the modem documentation or speak with the vendor to find out what type of serial card your PC has, and whether it is suitable for the modem you’re using.
Solution #5: Overheating Modems
External modems can become quite hot during their normal operation and may start to perform erratically if they overheat. Be sure to place your modem away from your PC, preferably in a well-ventilated area.
Solution #6: Modem Power Supplies
You should only use the power supply provided with your modem. Even though other power supplies might work, they may cause the modem to act erratically, resulting in slow speeds or disconnection.
Solution #7: Modem Error Correction
High data speeds require an error correcting modem. Ensure your modem has this feature enabled/turned on (usually found in the Control Panel under Modems).