For K56Flex modem operation, your modem must be operating with K56Flex v1.0 software or higher. In some cases this will mean your modem will require a flash upgrade and, in rare cases, a hardware exchange may be necessary.

To determine if your modem is K56Flex v1.0 you can place the modem in the command mode and communicate directly with the modem using the AT command set. To enter AT commands, you must attach your modem to a computer's serial port and enter commands directly from terminal emulation software such as Windows 95's HyperTerminal program.

To use AT commands in terminal mode to verify software version, do the following:

1. Start your data communications program.
2. At the screen prompt type in ATi3 followed by enter or a carriage return.
3. Note the modem's response on the computer screen.
4. If the modem responds with V1.0-56K_DLS (or higher), a K56Flex modem connection is possible.
5. If the modem responds with an earlier version of software (such as V0.519-K56_DLS), please contact the modem vendor's web site for the latest firmware upgrade. (See section: How can I get my K56Flex client modem upgraded?)

The quality of your K56Flex modem will be important to your downstream connect speed. K56Flex modems are responsible for compensating for the telco's human speech optimization of a voice call. K56Flex modems must be intelligent enough to differentiate between the maximum signal levels (up to 255 discrete levels) of a K56Flex connection, synchronize with the local telco switch, compensate for digital loss, determine if voice PADs are present, and handle whatever noise is present on the phone line.

In addition, the telephone company may place digital to analog conversions on the telephone loop between your phone line and our modems. The number of conversions will determine the maximum bandwidth possible for your call. It is possible that a call to one Internet Service Provider works for you at K56Flex speeds while a call to another provider will not work at such speeds. Calls to two different telephone numbers may travel over radically different telephone company equipment.

Where telephone lines do not have excessive analog to digital conversions, you will generally see a downstream speed of 42-52K and a maximum upstream speed of 33.6K.