ONTs use a passive transport (PON). ONTs are assigned time frames where they can send to the OLT (ISP equipment) that facilitates the connection. Incorrect equipment will cause that PON to become saturated by the ONT who decides to be malfunction and become a chatterbox. The OLT needs to be able to speak to the ONT to tell it to correct itself or shut up. Drift windows and Rogue ONTs are an issue.