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Q. Will I be able to connect at 56Kbps?

A. No. Public networks currently limit maximum download speeds to about 53Kbps. Actual connect speeds depend on many factors and are often less than the maximum possible. The following are some, but not all, of the many factors that could prevent a high speed V.90, K56flex, or x2 connection and result in a connect rate of 33.6Kbps or less. It is possible to have more than one condition present on your phone line.

  1. Multiple Analog Loops: In order to get a high speed (over 33.6Kbps) V.90, K56flex, or x2 connection, you must have only one analog loop in the circuit between you and your Internet Service Provider (ISP). Digital Loop Carriers are devices that are frequently installed in neighborhoods that may impose restrictions on the modem's performance by adding a second analog loop between your modem and the phone company central office. The phone line from your house is an analog line. Once the analog signal gets to the phone company central office, it is translated into a digital signal and sent out over the public network to your Internet Service Provider (ISP). Some signal data is lost in the translation - consequently, the more times the data is translated from analog to digital and back again, the worse the quality of the transmission. If there is more than one analog to digital conversion between you and the phone company central office, a high speed (over 33.6Kbps) connection may not be possible. The phone networks in older, heavily-populated areas utilize equipment that performs up to six analog to digital conversions.
  2. Incompatible Protocol: Your ISP must have "head-end" equipment compatible with the protocol of your modem.
  3. Phone Line Equipment: The primary purpose of the phone company's residential phone lines is to provide clear voice connections. Some equipment the phone company installs to make voice connections clearer actually can prevent high speed data connections. For example, your phone company may have installed a signal amplifier, loading coils, on the analog portion of your phone line. This equipment boosts Voice signal quality across longer distances, but causes some signal distortion and may inhibit your ability to achieve a high speed connection. Frequently, in newer neighborhoods, Subscriber Line Interface Circuits (SLICs) and Universal Digital Loop Carriers (UDLCs) are used to multiplex many residential copper lines to a central point whereby the voice traffic is sent back to the central office digitally. It is not possible to achieve high speed modem connections when connected to a UDLC. A SLIC does have some impediments to high speed connections, but if call signaling is set up properly (one or more bits may be "stolen" for the purposes of call signaling), high speed connections may be possible. Your phone company can determine if you are connected to a SLIC or a Digital Loop Carrier. SLICs appear as a small green box in your neighborhood. Some lines have installed a "pad" installed before getting to the phone company central office. The purpose of the pad is to equalize the volume on each end of a voice call. An analog pad introduces an additional conversion from analog to digital, and will prevent a high speed data connection. Contact your phone company for further information on your phone line.
  4. Long Distance Connection: A local access number does not necessarily mean a local call. Some ISP's use call forwarding to extend their geographical "reach". This may inhibit high speed data connections. Contact your ISP for further information.
  5. Other Electrical Equipment: Line noise can be added by additional phone equipment installed on your phone line. Disconnect any Fax machines, surge suppressers, Caller ID boxes, etc. and try again. Noise may also be caused by environmental factors such as power lines.

 

Data Terminal Equipment (DTE) Speed is the speed of the data transfer rate between your computer and your modem -- not between your modem and the phone line.

Data Communications Equipment (DCE) Speed is the speed at which your modem talks to another modem over the phone line.

DTE data transfer takes place inside your computer through a device known as a UART -- Universal Asynchronous Receiver/Transmitter, typically an 8250 series or 16450 UART for older '386 and '486 machines and a 16550 series UART for better '486 and newer machines.

The 8250 series UART transfers data at 57.6 Kbps. The 16550 series UART transfers data at 115.2 Kbps.

NOTE: Some browsers or communications programs are coded to display this DTE speed, not the actual speed at which your modem is communicating over the phone lines.

If you see a displayed speed of 115.2k or 57.6k, this is not the speed at which your modem is communicating with another modem over the telephone line!

What you are seeing is the DTE rate (the speed your PC is talking to your modem) instead of the DCE rate (the speed your modem is talking to the remote modem).

What you want to see is the DCE speed -- the communications speed that the two modems negotiate with each other when they connect.

There are two reasons you may be seeing the DTE speed in your modem's CONNECT message:

  1. The most common reason is that your modem is set to display the DTE speed rather than the DCE speed. Some modems display DTE speed by default. If you don't change the default, you will not be seeing the actual connect speed of the two modems. So the first thing to do is check your modem's manual and make sure your modem is set to display the DCE speed in its CONNECT message. The Aptiva Hardware Handbook or Aptiva Reference Guide that came with your system has information on changing the modem settings.
  2. The other reason for the display of DTE speed is using Windows 95 without having the proper .inf file for your modem. The .inf file lists all the CONNECT messages your modem can produce. If you have an outdated .inf file that does not contain the proper messages for your updated modem, Windows 95 can't figure out what is going on with the DCE speed, so it displays the DTE speed instead. The solution to this problem is to download and install the most current drivers for your modem. Data can be transferred at speeds such as 115.2 kbps or 57.6 kbps, but, again, this is an internal data transfer between your computer and modem that has no real relation to the speed at which your modem communicates through the telephone lines to another modem.

 

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