A Measure of Interconnection

From the News from 1930 blog:

By use of radio links, any Bell system phone can now connect to about 30M of world's 34.5M phones in 25 countries, including most of Europe and parts of South America and Africa, and to several ocean liners at sea. US-Europe are connected by 4 radio channels and so can have 4 simultaneous conversations.

I wouldn't expect a great expansion of phones to have occurred before 1941, so in my lifetime. we've gone from 30,000,000 to at least 3,000,000,000 (this source says there's 2.1 billion cell phones in the world now--add another 900,000,000 for land lines--my guess.)