Fixing frequent disconnects is difficult because you're not quite sure what is causing the disconnects. Contrary to popular belief, we generally don't bump people intentionally (although we know a couple ISP's around here do--we do not actively bump people unless necessary, like a problem with the line, modem or maintenance). It's bad business to do it on an intentional basis. There are several different reasons for disconnecting. First, there are scheduled disconnects. We call them scheduled because somewhere along the line something is timing out or reaching a limit. Examples of this are idle timeouts. An idle timeout is a setting on your modem or browser that is the amount of time a connection can stay open without data transfer. Internet Explorer has a default 20-minute idle timeout built into the browser, as does Microsoft’s dial up networking features. Now these things only work if there is NO data being transferred, so if you’re getting disconnected while downloading something, you have a connection problem that we'll try to fix here. The second type of disconnect is an unscheduled disconnect. Infrequent line drops are bound to happen due to irregularities along the telephone wire (we define infrequent as once in a while with no apparent pattern). Frequent disconnects will occur often over a single session (one night). When you're beginning to get aggravated, you're suffering from frequent disconnects. The local loop (our general calling area) on a scale of 1 to 10 is probably rated -5. The local loop is pretty bad as far as line quality goes. That's because many of our customers live in rural areas. When it rains or when it's cold and damp line conditions will be much worse than when the weather is good. There is nothing any other ISP or we can do about it but try to educate and make our networks as good as possible to compensate. While improvements are always working, everyone will drop a connection every now and again (happens to me) you aren't alone. With that said.... These steps are for those who suffer from more than usual disconnects. What we need to do is match modem settings to use the line rather than be abused by the line conditions. These settings are not guaranteed but they seem to have positive results most of the time.

If you are having a repeated pattern of disconnects the here are some suggestions:

With modems the most common cause of disconnects is connecting at TOO FAST a speed, causing frequent modem retrains, which in turn cause frequent disconnects. Most telephone lines will not support the maximum speed of the modem. With V.34 modems the best you should expect is 24,400 and any time you get a higher speed connection expect more frequent disconnects. With 56Kbps modems, the expectations are highly dependent upon how the Telephone Company has provisioned your service and expectations range from a low of V.34 speeds to around 48Kbps. Speed renegotiating is the most problematic code in modems and you can not rely upon it to hold a connection; in many cases it will fail and you will be disconnected. Try dropping your connect speed by forcing a lower speed, if that stops the disconnect then local loop line quality is most likely the problem.

The second most common cause of disconnects is modem incompatibilities, again typically related to re-trains. Get the latest firmware revision for your modem. Don't assume because you bought your modem recently it has current firmware. The statement 'my modem has no problems with xyz provider/service/modem etc.' is not particularly meaningful. Every modem will be compatible with someone, but we have yet to see the modem that is compatible with everyone. Our systems have been very reliable with current versions of firmware on modems from Hayes, Zoom, Supra, Motorola and many others... the biggest headaches come from the very low cost units like the WinModems that uses the PCs CPU to process data . As modems become faster they also become more complex. Some modems have a way to record the reason why a connection failed. Popular methods include the ATi2 or AT&V1 command (these are modem specific, your modem may vary).

Another common cause of disconnects is line noise. Unplug EVERYTHING connected to your phone lines: caller ID boxes, extension telephones, cordless telephones, other modems, fax machines. Also unplug your laser or DeskJet printer from the AC wall outlet. We have learned that many telephone line 'surge protectors' or 'noise filters' will seriously impair your phone line. The modem should be the ONLY thing connected to your phone lines... if the problem goes away... then you have something in your house causing you to disconnect. Do not route the phone line within three inches of any electrical cord or extension cord, or PC CPU cable, Printer cable, Monitor cable, any electrical appliance or power supply. Especially avoid laser and DeskJet printers, cordless telephones and uninterruptable power supplies (UPS's). Inductance from electrical lines and radio transmitters wreaks havoc with phone lines. This often means taping the phone line away from such places between the telephone jack and the modem or you may find a device actually connected to the phone line, which is causing you to disconnect.

If the line noise is not being induced inside your house it may be induced in the cable somewhere between your house and your local telephone exchange central office. Your line may have a one or more of conditions the telco calls 'bridge', 'ground loop', 'cross talk', or 'bad loading coil'. Any of these conditions will cause random noise and unpredictable disconnects. For noisy lines, try increasing a setting that tells the modem how long to wait (in tenths of a second) before hanging up when it loses carrier detect. This guard time allows the modem to distinguish between a line hit, or other disturbance that momentarily breaks the connection, from a true disconnects by the remote modem. For example: S10=100 setting will make your modem wait 10 seconds to make sure the other modem is really gone before hanging up. If this seems to help, contact your phone company and request the line be checked for noise at the demarcation block at your house. Do not let them just check the line from the central office end, ask to meet the repairman at your house and get him to report the results of his tests to you. If you encounter resistance from them because you have a modem, call back and tell them your fax machine is not working well with your phone line. Always be aware that the Phone Company is only required to provide for a 9600-baud connection. Beyond that they will tell you it is out of their control.

Sometimes defective cables and loose connections will cause disconnects. For external modems, if the serial cable is old, adapter pins bent, or cable cracked, replace it or try another one. Make sure your serial connections are TIGHT. Examine your telephone cable between the wall jack and the modem, or better still try replacing it. If portions of the telephone cable between the network interface and your wall jack have been stapled to the wall, examine the cable carefully. If possible try another jack or a jack on the telco network interface itself. This is box on the outside of your house that provides you phone service.

If you have call waiting, remember to add a *70, to the front of the OUHSC modem phone number to disable call waiting. Otherwise every time someone calls you, the modem will disconnect. We have had cases where the *70 could not stop the disconnects to troubleshoot this call waiting was temporally taken off the phone line.

You may have a hardware conflict. Frequently we have seen internal modem cards configured in conflict with another COM port which will seem to work OK for a few minutes of the connection and then just 'freeze up'. Check to see that your motherboard com2 port does not conflict with your modem, see your modem documentation for instructions on detecting and correcting IRQ conflicts. Also, if you have an Ethernet Card in your PC with an internal modem, it can certainly cause some problems with high-speed modem connections over 9600 baud. The only cure we have found is to remove the Ethernet card or use an external modem on a high-speed serial port.

Some PC's have built in idle timers. Windows 95, for example, has a 20-minute idle timer which is enabled by default when you upgrade your dial up network, install IE 4 or 5, and run the connection wizard.

Although rare, your modem may be set up to automatically disconnect after a certain period of inactivity. You may be able to fix the carrier loss problem by adding these settings to your modem initialization string: S19=0 This disables the inactivity time-out on most modems. If you want your modem to time-out and hang-up after a certain amount of time, you can replace the 0 with the number of minutes you want it to time-out after (up to 255 minutes.)

Generally, you should hold a connection for as long as you wish.... There will ALWAYS be an occasional disconnect; we are, after all, dealing with phone lines pushed to the very limits of their capacity when using the latest generation of modems. However, you should not get repeated disconnects. If you do something is wrong, and you should methodically follow the steps above to try to resolve the problem.

A common PC support problem we encounter at OUHSC is the subscriber's modem configured on an improper COM port. The resulting behavior will vary, but often the modem will connect and function properly at lower baud rates and not at higher speeds. Sometimes the modem will connect but will seem very slow, and often disconnect. Perhaps the modem will fail to connect at all, but the error message will not usually suggest that the modem is the problem (and while we're on the subject of error messages please realize that the messages reported by your operating system often times have absolutely no Bearing on what's actually happening -- the most frequent culprit being the message "The computer you are dialing is not answering" if your modem speaker is not audible and you get this message, when you pick up the phone to call the Help Desk dial the computer number your computer modem is dialing first to see if you get a computer tone on the other end if you do it will save us from having to put you on hold to dial that number first). Sometimes the modem will connect but the computer will 'freeze' (often when the mouse is being moved while the modem is receiving data, or when a large high color graphic is being displayed) and have to be rebooted.

The cause may be that the modem's COM port is conflicting with some other port on the computer. Internal modems usually will come from the factory preconfigured as COM2 or COM4. If the user has an existing I/O board or motherboard with a built-in COM2, this serial port should be disabled before installing the internal modem card at COM2. Sometimes the user will have had an internal modem at COM2 and add an external modem to an existing external serial port configured as COM2, which may not have been causing a problem previously but will now suddenly start causing a conflict. Since failing to disable an existing COM2 is a common oversight by users, many vendors have begun shipping their modems configured at COM4. This has introduced a new problem because many new high performance graphics cards can cause subtle conflicts with devices configured to use COM4. The COM4 conflict with graphics cards is often seen on systems configured to use Windows 95.

If you have installed a modem on your computer and it was not specifically checked for COM port conflicts, then you almost certainly DO have a conflict. Explaining how to resolve conflicts is beyond the scope of this paper. Your first step should be to consult the manual you received with the modem, or to contact the modem vendor's technical support department. Choose the particular COM port for your modem with great care. Modems installed on COM3 can often have performance problems as a result of sharing addresses with a serial mouse installed on COM1. COM4 may conflict with your graphics card.

Many newer systems and modems for use with MS Windows include support for a feature known as 'plug-and-play'. We have found allowing this feature to configure your modem automatically will sometimes introduce a wide range of very stubborn to diagnose connectivity problems. If you are having problems with your modem, and relying upon plug-and-play to configure its COM port, WE STRONGLY RECOMMEND YOU DISABLE PLUG-AND-PLAY ON YOUR MODEM AND MANUALLY CONFIGURE IT FOR COM2. This has proven to solve an enormous number of connectivity problems, which at first observation seemingly could have nothing to do with the COM port configuration.

Installing your internal modem on COM2 will almost certainly require you to disable the COM2 port on a serial I/O card or built-in serial port on your CPU motherboard. Even if you are installing an external modem on an existing built-in COM2 port, do not assume that the computer was originally configured correctly. We have seen many systems where there was a pre-existing conflict with a COM2 port on an add-in I/O card. The conflict went unnoticed until there was an attempt to actually use built-in COM2 port. If replacing an existing internal modem at COM2 with a high performance modem, don't assume that there cannot be a conflict. Sometimes a conflict will go unnoticed with a slow speed modem, but once a high-speed modem is installed the conflict will become apparent. We have even seen systems with a three-way conflict where a serial I/O card, built-in motherboard serial port and internal modem ALL have a COM2 enabled.

The best approach to installing a modem is to first disable the COM2 port on your system and then check to see that your system actually does report that it cannot find a COM2. Then install the internal modem at COM2 or re-enable the COM2 port and install your external modem.

The most likely cause of these disconnects is simply that your phone line can't reliably support the speed at which your modem is connecting to OUHSC. The faster your modem communicates with OUHSC and the more data transferred, the more likely you will be to be disconnected. Basically OUHSC and your modem are outperforming your phone line. Your telephone company states your line is good for data transfers up to 9600 (9.6) NO HIGHER, although your modem manufacturer will tell you its good for 56Kbps. The reality is somewhere between, about 26.4Kbps. If you are connecting to OUHSC at speeds greater than 26.4Kbps and live more than a few thousand feet from your local telephone exchange, then you will experience poorer performance and more frequent disconnects.

Right now you want to scream But I N*E*V*E*R get disconnected when I call someone else, and you are absolutely right. That’s because your modem connection is running at a slower speed when communicating with systems other than OUHSC. But unfortunately with most modems you have no way of knowing the true communication speed, only the initial connection speed at best that value is typically only true for a few seconds before it will change.

OUHSC’s telco service is all noise-free digital signals resulting in our end having the best connection quality the telco is capable of providing to a subscriber. The local exchanges communicate between themselves using this same technology, so there are normally not problems with that segment. This leaves the local loop between the subscriber and their telco central office as the only remaining segment which is likely to affect connection quality. This situation of having two thirds of the connection path be digital, results in calls to OUHSC often training at the maximum speed the modem will support. But our experience is that the connection will quickly retrain due to the quality of your local loop once data begins flowing between OUHSC and the computer.

You can't detect the retrain, its something invisible happening between the two modems, but after the retrain the modems are usually running at a different speed. Heavy data flow is the situation most likely to cause a retrain. More data transfer = more data errors = retrain). What’s happening is a sort of yo-yo effect. The modem trains to a speed which is too fast, data flows, errors occur, the errors trigger the modems retrain to lower speed, resulting in fewer errors, things are good for a while so the modems retrain to a faster speed, where errors start to occur causing the modems retrain and so on. The modems are not supposed to constantly retrain, they have rules in the firmware of the modems to minimize constant retrains but our experience in the field with this is it happens a lot anyway, especially over longer calls. Retrains are very complex events and some of the most bug infested code in modem firmware, eventually one of the retrains fails and you get disconnected.

This is why long file transfers result in disconnects. So everything was fine, and suddenly you are getting more disconnects. The chances are your phone line quality has changed. It may have gotten slightly BETTER, particularly if it’s been dry and/or cold for a little while. Perhaps your line may have gotten slightly worse, for a huge list of reasons but especially if its been wetter or warmer than normal recently. But just a tiny change either way will simply fool you modem into training to a speed the line will not actually support and the retrain yo-yo problems begin. You can avoid a lot of disconnect and performance problems by forcing your modem to train up to only a certain speed and no higher. This is not the same as setting your port speed. The only way to control the connection speed is to use modem init string options to disable the modem's ability to train higher than a certain maximum. This can be a rather tedious task you must figure out where the modem init string is stored in the software and then you have to figure out the actual init option. Determining what value to use can be mostly trial and error. Start with a serial port speed of 38.4Kbps and a maximum dial connection speed of 24Kbps. We understand your frustration and want to help.

Run modem diagnostics

Some modem brands, such as US Robotics products, have line diagnostics that can be employed after a disconnect to determine the cause of the drop. It may be helpful to consult your manual to see if this feature is available.

You probably know this already, but you should disable call waiting. The "click" of an incoming call may disconnect you, though newer modems have improved error correction that is less sensitive to this.

In most areas, you can disable call waiting on a touch-tone line by placing *70, in front of the phone number, like so:

*70,271-8670

If your lines do not have touch-tone service, and instead use pulse dialing, the command is 1170.

Note that in some areas, the phone company charges you each time you disable call waiting. Also, some areas use different commands, or may require you to request the ability to disable call waiting. If in doubt, call your phone company.

Upgrade firmware, init strings, and drivers

Many disconnect problems can be solved by loading a more recent version of the firmware. Likewise, having the correct modem init string or driver installed is important.

Try unplugging any devices from the back of the modem

Modems have two phone jacks on the back: one is for the line connected to the wall jack. The other is for plugging in a telephone, answering machine, fax machine, etc.

Try unplugging your telephone or any other device attached to the back of the modem. Some devices may cause problems. For instance, some telephones draw power from the phone lines every 15 minutes to power the circuits that keep track of speed dial numbers.

It's possible to have too many devices on your phone lines or extension. Try unplugging extra phones, fax machines, and answering machines to see if the disconnects stop.

Older PCs may have weak UARTs that are not capable of high-speed communications. As a result, you may get frequent dropped connections and/or poor modem performance due to resent packets.

To test this, try lowering your port speed to 38400 or even 19200. If the dropped connections cease, a slow UART may be the problem. A replacement serial port card should fix the problem.

For use with a 56K modem, you want at least 16550 UART. Internal 56K modems should include a 16550 or higher UART on the card.

Some K56flex owners have found that they can reduce disconnects by setting a limit on the initial connect speed. The commands for controlling maximum connect speed are different for Rockwell-based and Lucent-based K56flex modems.

If you normally get disconnected when you connect at 48000, you might try using:

+MS=56,0,9600,46000

If that didn't work, you would try:

+MS=56,0,9600,44000

+MS=56,0,9600,42000

and so on, reducing the maximum connect speed by 2000 each time. Experiment with different numbers to see if lower numbers result in fewer disconnects.

If the modem supports V.90, use the +MS=12 command (see above for instructions):

+MS=12,0,9600,46000

The S38 command can be used to control the maximum connect speed. The values between 2 and 14 set the maximum speed between 32K and 56K. So, if you normally get disconnected when you connect at 48000, you would try:

S38=9

to set the maximum connect speed to 46000. If you still get disconnected, you might try:

S38=8 (for 44000)

S38=7 (for 42000)

and so on.

This is the x2 version of Spiral Death Syndrome. The fix in most cases is to add S15=128 to the init string to disable V.42 hardware error correction. It may also be necessary to add &K0 to the init string to disable V.42bis hardware data compression, though this should be a last resort, as performance will suffer when downloading non-compressed files.

Turn off the television, stereo etc. Connect a regular (hardwired, not cordless) telephone handset with clean "hook" contacts to the data line. Pick up the handset, dial 1 (this will silence the dial tone) and listen very carefully. If you can hear a lot of hiss or, more likely, an occasional "scratching" noise, there is definitely a line problem and you should report it to SWBT. Unfortunately, a line that sounds "quiet" may still be faulty. Some modems provide quantitative readout of signal strength and line quality. Consult your modem manufacturer's documentation for details. This can be useful in diagnosing.

Fax software is particularly tricky, as they often have a tendency to 'baby-sit' the modem connection, waiting for incoming communications. As a result, they can sometimes mistake a regular modem connection for a failed attempt at a fax.

Modems do go bad, and even brand-new modems may have been on the shelf for a long time. If you have another modem somewhere, try the other one to see if you are having the same problem.

I will end this with a question I hear all too often.

Question: I bought an inexpensive modem but it keeps cutting me off. Is there something wrong with it?

Answer: Probably. The old adage in the on-line world is "Buy a $29 Modem, get a $29 Connection!". The shortcuts necessary to bring the cost of a modem down often result in unreliability of those components. Our advice is always: "beware of very inexpensive modems. Most often you get exactly what you paid for." While a $150 and a $300 modem may offer the same functionality, they are likely to differ in everyday use. Some lesser brands may have difficulties negotiating the connection, and sometimes you may have to dial the other end two or three times before the connection is established. Once established, the connection may not hold very reliably, and small noise on the line may disconnect you. However even the best modem can not cope with wrongly configured system or very noisy phone line.

Why you don't get 56k (review by Katie Barns for Cnet.com)

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