Power utilities employ a wide variety of telecom technologies in their operational communication networks. These technologies, which evolve over time, are extensively documented in general telecom literature and their detailed analysis is beyond our present scope. A short overview of some major ones used at present is given here. Copper wires are not considered in this work and PLC is only analyzed as far as new technical advances are concerned. The concepts and terminologies introduced in this section are used across the book, even in preceding parts.