Satellite links have long been used to carry telephone calls to extend the reach of public and private networks. This role has changed over the years due to the adoption of digital transmission and fiber optic systems throughout developed countries. During the 1990s, undersea fiber was introduced on a global basis and so the original demand for satellite telephony has diminished. Another trend that has been underway is the rapid economic expansion of many underdeveloped countries throughout Asia, Africa, and Latin America, as well as increased inhabitancy of rural areas of developed countries. Owing to the Internet, the telephony sphere is undergoing a transformation in the form of VoIP technology for connecting calls through this pervasive medium.