when operating with poor line quality.

If the telephone line drops out, MNP 10 will attempt to reconnect up to the maximum time permitted by your country’s telecommunications rules. Thus, if there is a short line drop-out, MNP 10 will provide minimal interruption whereas other modems will disconnect entirely.

MNP is the only type of error correction allowed with MNP 10 and is only available when connected to another modem that supports MNP 10. The #K command is used to select MNP 10.

Speed Changes

Although MNP 10 is able to cope with bad telephone connections, your modem must be able to first make a connection with another modem before it can make use of MNP 10. For this reason you may wish to use the AT%H1 command to force your modem to connect at 1200 bps and then ‘upshift’. Most telephone lines will cope with V.32 or V.32bis connections, however connecting at 1200 bps will ensure you make a connection. You may also use the J dial modifier to force your modem to make the initial MNP 10 connection at 1200 bps.

When MNP 10 changes line speed (either up or down) there will be a slight interruption to your communications. For this reason you should always use flow control to ensure data is not lost when MNP 10 changes line speed.

If you wish to establish the connection prior to MNP 10 upshifting or downshifting, issue the %H9 command. This allows you to use the connection before MNP 10 attempts to change the connection speed.

Cellular Modem Users

If you are making modem calls with a cellular phone, issue the AT#K2 command. This tells MNP 10 to try even harder to maintain the connection if your cellular call momentarily drops out.

With such a choice, you may be wondering which combination you should be using. The table below shows the relative performance of each combination of error connection and data compression.

If you are connecting to various makes and models of modems, V.42/V.42bis auto-reliable mode is probably the best alternative (AT\N3%C2). V.42/ V.42bis auto-reliable mode will also connect to another modem that supports MNP with V.42bis data compression. For overseas or cellular connections, use MNP 10 if possible (AT\N3%C2#K1).

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Telenetics 56 manual Speed Changes, Cellular Modem Users