How to - Troubleshoot Modem Disconnects

56K modem technology uses regular phone lines to obtain speeds comparable to single channel ISDN at a lower cost. Two different types of 56K technologies were developed, K56flex and X2. These technologies have been replaced by the v.90 standard, which Quantum currently supports.

Although users may experience problems when using 56K modems, most will find them an economical way to boost surfing speeds. Problems that some users will experience may be because of their location in relation to their phone company's Central Office (CO). Some phone companies (including Verizon) have designed networks that utilize remote terminals, which create additional analog/digital conversions in the circuits between their customers and the Central Offices (COs). Because of these additional analog/digital conversions, the chances of obtaining a 56K connection is a hit-or-miss proposition, but fast connects are still attainable in many regions. Additionally, some compatability issues exist because v.90 is still an immature standard. This page may be a valuable resource for fixing many types of connection problems.

If you are thinking about buying a modem to connect to Quantum's service, we recommend:

• Zoom 56K (Lucent-based)

Generally, if you are within 2-3 miles of your phone company's Central Office, it is likely that you will be able to use a 56K modem successfully. Even if you are farther away from your CO, you may still be able to use a 56K modem if the analog/digital conversions described above are not present.

If you are having problems with your v.90 56K modem, please try the following before contacting technical support:

• Check your phone line for noise
• Upgrade your modem's firmware
• Limit your modem's highest connect speed
• Disable 56K technology

Line Quality Check

To check for noise on your phone line, plug a telephone into the same jack as your modem. Pick up the handset and dial a single key on its keypad. Listen for any noise. You should hear dead silence. If you hear any hissing, scratching, humming or crosstalk, you will need to have the phone company check out your line. Even the most faint noise will impair your modem. Insist on a noise-free line from your telco.

Firmware Upgrades

Upgrading your modem's firmware can solve disconnection problems as well as failed connections. It is recommended that you upgrade your modem's firmware before contacting Quantum for technical support.

If you would like to determine your modem's firmware version, please follow these instructions:

Windows 95/98:

Click on the START button, then SETTINGS, then CONTROL PANEL. Double-click on the MODEMS control panel. Click on the DIAGNOSTICS tab and then click on the COM port of your modem. Click on the MORE INFO button. For Rockwell and Lucent chipset modems, the firmware version will be listed on the line labeled ATI3. For U.S. Robotics and other USR-based modems, the firmware version and DSP revision date will be listed on one of several lines labeled ATI7.

Recommended minimal chipset firmware versions:

• Rockwell chipsets: 2.100
• Lucent chipsets: 5.18
• U.S. Robotics chipsets: firmware dated 6/98 or later

For your convenience, we have listed the locations of firmware upgrades for several of the more popular modem manufacturers. If your modem is not listed here, please check http://www.56k.com/links/Firmware_Updates/.

• Zoom
• Diamond Supra
• Lucent/LT Winmodem
• 3COM/U.S. Robotics

Limiting Connect Speed

If upgrading your modem's firmware did not seem to solve your connect or disconnect problems, you should try to limit the maximum connect speed of your modem. You will need to add an additional init string to your modem. If you do not know how to do this, 56K.COM has an excellent tutorial. If you are using a Mac, click here for the Mac tutorial. If you are using Windows 95/98, click here for the Windows tutorial.

If your modem is a Rockwell-based v.90 modem, the format of the init string is:

+MS=12,1,LOWSPEED,HIGHSPEED

Substitute LOWSPEED for the lowest speed you want your modem to connect at (usually 9600). Substitute HIGHSPEED for the highest speed you want your modem to connect at. We recommend that you start out setting the high speed to two speeds slower than what you normally connect at. For example, if you normally connect at 48000, you should try +MS=12,1,9600,45333 to connect at 45333.

If your modem is a Rockwell HCF v.90 modem, the format of the init string is:

+MS=V90,0,TXLOWSPEED,TXHIGHSPEED,RXLOWSPEED,RXHIGHSPEED

Substitute TXLOWSPEED for the lowest upload speed you want your modem to connect at. Substitute TXHIGHSPEED for the highest upload speed you want your modem to connect at. Substitute RXLOWSPEED for the lowest download speed and RXHIGHSPEED for the highest download speed. For example, if you normally connect at 48000, you should try +MS=V90,0,9600,33600,19200,45333 to connect at 45333.

If your modem is based on a Lucent (LT) chipset, use the following init string:

-V90=n

Substitute n for one of the values in the following table:

For example, to limit your USR modem to a maximum connect speed to 45333 and a minimum connect speed of 28800 use &N30&U17.

Disable 56K Technology

If you are still having problems with your 56K modem, you may want to disable its 56K technology. This will limit your modem's speed to a maximum of 33,600 bps. To disable 56K, find your modem's chipset in the following table and use the corresponding init string: