A fiber termination device installed at the subscriber's premises.
Short for Optical Network Unit. A device installed at the subscriber's premises that converts the optical signal to an electrical signal and hands it off to a router or similar device. Often used roughly interchangeably with ONT (Optical Network Terminal). Because an ONU needs household power to operate, a power outage takes down not just internet access but any IP phone service riding on it -- a point often raised when customers migrate off traditional copper lines.
© 2026 ITBGM