Telecommunication Engineers are concerned with establishing communication by means of telephones, telegraphs, radar, radio, radio navigational aids, TV, and teleprinters. Important towns, cities, trade centers, harbors and ports are connected with underground cables or radio links. Countries and continents are brought closer by means of fast-emanating, information-carrying communication networks. All this has been made possible by the telecommunication engineer. Telecommunication engineers deal with line and wireless communication, or radio communication. Line communication is handled by telephone/telegraph engineers. The work comprises the installation, supervision, and maintenance of telephone exchanges and telephone lines. The radio communication engineer's work is concerned with the designing, installation, maintenance and periodical testing of broadcasting and telecasting systems and studios, and transmitting and receiving stations.