An optical line terminal for interfacing with any of a plurality of types of optical modules, wherein each of the types of optical modules corresponds to a respective optical protocol or combination of optical protocols for communicating with a plurality of optical network terminals through an optical network, comprising: a socket for receiving an optical module; optical line terminal OLT circuitry configured to encapsulate first data for transmission through the optical network and to communicate with the optical network terminals for controlling upstream transmissions through the optical network by the optical network terminals, the OLT circuitry configured to transmit the first data and the first control information to a first optical module mated with the socket, the OLT circuitry configured to receive second data and second control information from the first optical module; and a controller configured to control the OLT circuitry to selectively operate in a plurality of operational modes, including at least a first operational mode and a second operational mode, the controller configured to identify a module type for the first optical module and to select one of the first operational mode and the second operational mode based on the identified module type, the controller further configured to control the OLT circuitry to operate in the selected operational mode when the first optical module is mated with the socket, wherein the OLT circuitry is electrically and operationally compatible with a first type of optical module when operating in the first operational mode, characterized in that the first type of optical module corresponds to Multi-PON protocol, wherein the OLT circuitry is electrically and operationally compatible with a second type of optical module when operating in the second operational mode, and wherein the socket has a receptacle for receiving a pin of the first optical module, and wherein the controller is configured to control the OLT circuitry such that the receptacle is electrically coupled to ground of the OLT circuitry when an optical module of the second type is mated with the socket and the receptacle is electrically isolated from the ground of the OLT circuitry when an optical module of the first type is mated with the socket. a socket for receiving an optical module; optical line terminal OLT circuitry configured to encapsulate first data for transmission through the optical network and to communicate with the optical network terminals for controlling upstream transmissions through the optical network by the optical network terminals, the OLT circuitry configured to transmit the first data and the first control information to a first optical module mated with the socket, the OLT circuitry configured to receive second data and second control information from the first optical module; and a controller configured to control the OLT circuitry to selectively operate in a plurality of operational modes, including at least a first operational mode and a second operational mode, the controller configured to identify a module type for the first optical module and to select one of the first operational mode and the second operational mode based on the identified module type, the controller further configured to control the OLT circuitry to operate in the selected operational mode when the first optical module is mated with the socket, wherein the OLT circuitry is electrically and operationally compatible with a first type of optical module when operating in the first operational mode, characterized in that the first type of optical module corresponds to Multi-PON protocol, wherein the OLT circuitry is electrically and operationally compatible with a second type of optical module when operating in the second operational mode, and wherein the socket has a receptacle for receiving a pin of the first optical module, and wherein the controller is configured to control the OLT circuitry such that the receptacle is electrically coupled to ground of the OLT circuitry when an optical module of the second type is mated with the socket and the receptacle is electrically isolated from the ground of the OLT circuitry when an optical module of the first type is mated with the socket.