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.
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.
Protocol: Your ISP must have "head-end"
equipment compatible with the protocol of your modem.
- 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.
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.
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.
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.
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.
Some browsers or communications programs are coded to display this
DTE speed, not the actual speed at which your modem is communicating over the
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
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
There are two reasons you may be seeing the DTE speed in your
modem's CONNECT message:
- 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
- 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.