This Recommendation gives a procedure for the protection of telecommunication lines using metallic conductors against direct lightning discharges to the line itself or to structures that the line enters. The protection procedure is related to the exposure of the line to direct lightning discharges and includes the selection of cable characteristics/installation, bonding/earthing of the cable shield, use of shield wires, lightning protective cable, steel tube, lightning protective cable duct, installation of surge protective devices (SPD) and route redundancy. Examples of application of this Recommendation are reported in Appendix III.