A linefeed on a subscriber loop is generated to generate a current on the subscriber loop. Whether a relationship between a voltage on the subscriber loop and a threshold voltage for an identified range of voltages satisfies a condition is identified. The linefeed on the subscriber loop is controlled to modify the current on the subscriber loop in response to identifying that the relationship between the voltage on the subscriber loop and the threshold voltage for the identified range of voltages satisfies the condition to help generate the voltage on the subscriber loop in the identified range of voltages. The identifying and controlling are continued to help generate and maintain the voltage on the subscriber loop in the identified range of voltages.