Q. What is V.90?

A. An International Telecommunication Union (ITU) committee agreed to a draft standard for high-speed PCM (pulse code modulation) modems early in February 1998. This standard is called V.90 and was ratified late in 1998. V.90 is a protocol that allows two earlier PCM Protocols, K56Flex and x2, to interoperate with each other after they have been upgraded to V.90. Interoperability is a key factor that enables many different modem brands to connect. Like previous PCM protocols, V.90 is asymmetric. This means that your modem can receive data at a rate faster than that at which it sends data.
ISLC accepts V.90 protocol; however, some 56K modems may not connect with an appropriate connection until they have been upgraded to the new standard.

A. 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.

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 (such as ISLC). 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. This situation occurs for barracks quarters on Parris Island using AT&T as the phone service which is then switched to Sprint.

2. 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.

3. 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. ISLC does not use call forwarding.

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, line work in your area, etc.

Q. How do I upgrade my system to V.90?

A. Your 56K modem may be ready for V.90, especially if it is a new computer. Many systems have flex-based 56K modems that may have older driver files (file dates are previous to October of 1998, approximately). You should check with your computer manufacturer (many have websites) to see if your modem has the latest driver. We suggest you download your driver from your manufacturer's site; often there will be other files such as sound drivers associated with your modem driver files. Try these sites for the following computers: (more will be added)
Compaq Presario modems
IBM Aptiva Lucent modems
Hewlett Packard
Diamond Supra modems
AcerOpen

Download the driver for the LT Winmodem and the Gateway Internet modem by clicking here Modem Drivers.

Q. What are DTE and DCE Speeds?

A. There is an important difference between DTE and DCE.

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 (like your modem to the ISLC modems) over the phone line.

DTE data transfer takes place inside your computer through a device known as a UART -- Universal Asynchronous Receiver/Transmitter. Data transfers occur either at 57.6 Kbps or 115.2 Kbps depending on the UART series.

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. In Windows95/98, locate the 2 computers on the right-hand side of the task bar while you are connected to ISLC. If the displayed speed is 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 (which usually comes with your new computer) and make sure your modem is set to display the DCE speed in its CONNECT message.

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.