The invention is directed to an optical network terminal (ONT) for use in a passive optical network (PON) that provides reliable battery status reporting and, optionally, remote monitoring and configuration of an uninterruptible power supply (UPS) unit. In particular, the UPS unit provides power to the ONT via a power line and transmits data to the ONT via the power line. Generally, the described invention supports one-way or two-way communication of status, alarm, and configuration signals using a single power line. Specifically, such signals may be transmitted over the power line by inserting a carrier frequency, such as a carrier frequency of approximately 1 MHz, onto the power line. In this manner, the invention may provide a simple battery status monitoring system while also reducing the cost of installation.