Wireless networks, satellite data connections and use of optic fibre represent the most up-to-date telecommunication trends. Even if it appears so, this is not the ultimate end to metallic telecommunication structures. Metallic data connections are still irreplaceable in automation and signalling systems, phone lines and telephone exchanges. And this is despite the fact that the “traditional” analogue voice telephony and the related data transfers are continuously being replaced with digital forms. Thanks to technological progress allowing higher data transmission efficiency off metallic telecommunication connections, even these cable lines can today be used for the provision of high-speed data services without any considerable limitations. For data transmissions, companies use existing or newly built cable routes of copper (e.g. the national Telco operators, railway companies, big manufacturing companies), believing that the advantages provided by metallic networks will be usable in future too.