Recommendation ITU-T L.MandM networks provides a set of metrics for the assessment of energy efficiency of TLC mobile networks, together with proper measurement methods. Such metrics are of extremely high importance for Operators, provided that the optimization of the energy performance of single equipment does not guarantee the overall maximum energy efficiency of a complex network formed by several equipment interconnected. Hence, through the metrics reported in this Recommendation, a better comprehension of networks energy efficiency will be allowed, not only for "total" networks, but also for "partial" networks, definable through either geographic or demographic boundaries. In a further step, energy efficiency of TLC fixed networks will be provided.