The model of an ideal (without an intermediate layer and electron surface states) metal-semiconductor Schottky-barrier contact is numerically analyzed with allowance for the effect of image-force barrier-height lowering. It is shown that the nonlinear dependence of barrier height on the bias voltage inherent in this contact causes not only the deviation of the current-voltage (I-V) characteristic from an ideal one but also the so-called “low-temperature anomaly” — an increase in the I-V-characteristic ideality factor n and a decrease in the barrier height ϕbm measured from the saturation current as the temperature is decreased. A more exact equation for the I-V characteristic of the ideal contact is theoretically substantiated using parameters n and ϕbm in a wide temperature range.