TeleGeography has published regular data on the international communications market. The report says that in the past two years, growth in international voice traffic has slowed to 8 percent (in the past 25 years, the average annual growth has been at 15%).
At the same time, the volume of calls made via Skype is growing, picking up the pace. In 2008, the volume of calls between Skype users grew by 51% in 2008 and by 63% (estimated) in 2009.
In 2009, TeleGeography estimates that the total volume of international telephone traffic was 406 billion minutes, and the volume of Skype calls was 54 billion minutes.
Graphically, it looks like this:

TeleGeography analyst Stefan Beckert says this makes Skype the largest international communications provider in the world. In general, the development of alternatives to traditional calls (and this is both Skype for mobile phones and Google’s penetration into this market) means that international operators have difficult times. For example, the volume of calls to Mexico (and this is the most popular direction of international telephone communication) fell by 4% (and by 5% to the countries of Central America as a whole).
Read more - here:
http://www.telegeography.com/cu/article.php?article_id=31718&email=html
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http://www.telegeography.com/product-info/tg/index.php