What is the impedance of the Line Interface and the current drawn?

The amount of line current is based on variables to the basic formula E=IR.

The modem's line interface dc impedance is either 200 or 300 ohms.

The max line current (dc current draw) the MT2834MR supports is 60ma. R(resistance) is derived by adding the impedance of; the dc source, the modem, and the physical wires\path between the modem and source.

There may be some small differences in the supported max line current - between the various models (MR vs MR6 vs MRK etc).