The ITU workshop The Future of Voice held on the 15th and 16th of January 2007 in Geneva, Switzerland looked, inter alia, at the voice traffic and revenue trends in the last fifteen years. On the global level, local and national long-distance reported telephone minutes per capita were growing in the 1990s and stably falling since the beginning of the new decade. A notable exception of the general rule is the US experiencing continuous growth in the number of local minutes: in 15 years, the number of local minutes per capita has grown four-fold. The international outgoing traffic grew significantly over the last fifteen
years: in the Republic of Korea, in 2005 it was 15 times more intensive than in 1990, in the US – five times. Even though, since the beginning of the new century, the international voice traffic tends to slowly decrease.
http://www.itu.int/osg/spu/newslog/Voice+Revenues+In+The+Telecommunications+.aspx
