From one side gravity suggests that quantum field theories are low energy approximation of a more fundamental theory, on the other side phenomenology tell us that we need to go beyond the standard model. Neutrino physics is one of the most important motivation besides baryon asymmetry and the dark problem. In this talk I focus on the origin of neutrino mass from a model building point of view and I discuss possible way and strategy of extension. As an example I show the case where the electroweak group SU(2) x U(1) is extended to SU(3) x U(1). This model is named 331.