It was about 2000 at which point internet use was a big part of our lives and, usually, was flat-rate. Thus, if you accept that "telecommunications" includes the internet, his prediction of flat-rate global communication has come true.
We use github and code.google.com and other systems to collaborate globally without realizing how amazing that it. In 1999-2001 when Christine and I wrote TPOSANA the publisher was amazed at how we did all our collaboration over the internet; it was still a relatively new thing. Today we take it for granted.
When I see a project like Playing For Change it makes me optimistic about the other part of Asimov's prediction: