in the past when many countries, for example the communist block, limited christian activities, the missionary stations were very active in broadcasting in many languages and to many places.some of these countries now allow more local christian activity. however other countries still limit the work of missionaries and so radio is still used. in some countries only government stations can operate. stations outside the country are the only way to provide service into those countries. to provide the longer range coverage, shortwave is often used by missionary stations, although super power am is also sometimes used.