A system and method for registration of network units is disclosed. A system that incorporates teachings of the present disclosure may include, for example, an optical network unit (ONU) in a passive optical network (PON) that can have a controller element to receive a registration code, send the registration code and a serial number of the ONU to an optical line terminal (OLT) that configures the ONU for temporary connectivity with the PON, and upon an expiration of the registration code or a termination of the temporary connectivity, re-send the serial number to the OLT to re-configure the connectivity with the PON. Additional embodiments are disclosed.