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BOCA PRO16 Reference Guide
become acceptable. Similarly, if the line quality improves and the
modems are using the largest packet sizes, the modems will ‘step-up’ in
speed until the best compromise of error rate and line speed is found.
MNP 10 will also make multiple attempts at establishing an error-
corrected connection to another modem (more so than MNP 2-4). This
gives you a better chance of making a connection 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 dis-
connect 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.
Error Correction
Error
Correction
pro16ref.pm6 6/14/96, 2:36 PM31
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