Methods and systems for implementing versatile optical terminals that detect optical transmission protocols and subsequently adapt to the correct protocol are disclosed. In an embodiment, an interface device for providing an interface for a first network with a passive optical network (PON) is disclosed. The interface device includes a protocol detection circuit for determining whether optical communication signals received from the PON conform to a first optical communication protocol, and a switchover control circuit that reconfigures the interface device to work with a second optical communication protocol when the received optical communication signals do not conform to the first optical communication protocol.