Why don't I ever get connected at the speed my modem says it can go?

Some of the following information is excerpted from the excellent Navas 28800-56K Modem FAQTM

Sometimes internal cards can interefere with each other, especially if less than ideal components are used. Try keeping your sound card and modem card on opposite ends of the card bay in your computer.

If you see a connection speed of 38400, 57600, or 115200, don't be fooled -- that is the serial port speed between your computer and your modem, not the speed between your modem and the remote modem. To report the modem-to-modem speed, your modem probably needs a different initialization string. Consult your documentation.

Reported initial connect speeds won't necessarily be dependable or even comparable from modem to modem or location to location. The reason is that V.34 modems can (and often do) speed shift up and down after the initial connection, and do so in a manner that is dependent on the particular connection as well as the particular equipment (including firmware versions) at each end. Some modems connect at a more conservative speed and then quickly upshift as conditions allow; other modems connect at a more aggressive speed only to quickly downshift (or worse, lose performance due to excessive errors). Another problem is that software may report the receive speed for certain modems and the transmit speed for other modems, which can be substantially different. Unfortunately, it is not possible to monitor the actual modem speed during the connection for most modems. Regardless, the only thing that really counts is net throughput, which can be measured by many communications applications.

If you consistently connect at 26400 or above, there may not be much that you can do to go faster -- it's simply not possible to achieve the highest V.34 speeds on many phone circuits. (This is not false modem advertising -- 28800 modems are designed to wring as much speed out of the actual real-world connection as possible, and 28800 or higher speed is only possible on a near-perfect connection.)

If you consistently connect at lower speeds (e.g., 24000 or even 21600), there may still not be much that you can do, but you can at least try the following:

• Make sure that your serial port is locked at 38400 or higher (57600 recommended). This is usually set within your comm application, not the Windows Control Panel (see " How do I set a speed greater than 19200 bps in Windows?").
• Watch out for heat. Some modems work better cold than hot, and vice versa. Generally speaking it is a good idea to make sure that the modem does not get too hot.
• With a PC Card (PCMCIA) modem in a laptop computer, try disconnecting the computer from AC power and running on battery alone.
• Try connecting to known good 28800 numbers (e.g., Hayes at 800-"US-HAYES; Multi-Tech at 800/392-2432; USR at 847/982-5092). This will at least tell you whether the problem is at your end or the other end of the connection. (The USR number is particularly useful, because you can get an on-line reading of connection quality from a USR BBS command.)
• If you have your modem connected to the phone line through a surge suppresser, try it without the surge suppresser. Many surge suppressers can interfere with modem communications.
• If possible, test for premises problems by disconnecting all your premises wiring (and equipment) from the incoming telco terminating block, and hooking your modem directly to it. If your connections are better, you have a premises problem that you may be able to isolate and fix. Premises problems (faulty wiring and/or equipment like cheap phones and fax machines, and even other modems) are a frequent cause of connection problems. If you need to fix your premises wiring, you can get help at the "Phone-Man's Home Page".
• If that doesn't help, listen carefully to the quality of your voice connections. Note that you must dial a known quiet number, since many otherwise good phone lines exhibit excessive noise until you actually connect. (Dialing a single digit is not enough.) After you connect, if you hear more than very faint hiss and/or hum, then you probably have a line problem.
• While a quiet line is important, there are other line problems that can reduce your speed: bandwidth (frequency response), distortion, etc. It is difficult to test for these problems without proper test equipment, but it's still a good idea to listen carefully for audible problems, particularly if you can find a number that will send you test tones.
• You may be able to get your phone company to improve the quality of your line. Since phone companies are often reluctant or even unwilling to work on data problems, it may help to report that you are also having fax problems. Or you can try asking for a data or fax "specialist." Ideally you want the service technician to bring the right kind of test equipment, a sophisticated line or transmission test set, not just the normal basic tester. It may also help to ask for a BERT (bit error rate tester) or "data test set."
• Sometimes switching to a different cable pair from the CO (central office) will help. In extreme cases the author has resorted to ordering a new line, making sure that it is good when installed, and then canceling the old line.
• You may be told that you need a special "data" line, more properly called a "conditioned" circuit, which is considerably more expensive than a standard "voice-grade" circuit. Don't waste your money. All you need is a good quality "voice-grade" circuit.

Those with a technical bent may be interested in the telecom troubleshooting information posted in the Technical Bulletins by Mike Sandman, who sells a variety of hard-to-find telecom tools, parts, and test equipment.

A final note: Common add-on noise filters will not help -- they are the modem equivalent of snake oil. Your 28800 or better modem already has all the filtering it can use. A common add-on filter will do nothing at best, and it may well make things worse.

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