Perle 833IS, User Manual

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Configuring the Perle DSP Modem Interface
88 Perle 833IS User Guide
V.90 Modems A V.90 modem obtains its high data rates by treating the analog data line as an
imperfect digital line. This "digital line" appears to the modem as having a number
of impairments, and the modem during negotiation attempts to determine what
impairments exist, then compensate for them. Certain connections (for example,
some GSM modem connections) can trick this negotiation. If this occurs, either the
modems will not negotiate, or they will connect, but the data error rate will be so
high as to make the connection impractical.
If these problems are encountered, it is necessary to prevent the modems from
attempting to negotiate V.90. Modems have parameters that can be set to disable the
V.90 modem. This can be done either in the client modem or by setting the Modem
Initialization String in the 833IS modem.