Here's an interesting thread to read in the Skype User Forums:
The "Reader's Digest" version is that until late last year, Skype offered an "Unlimited Calling Plan", for $15 a year or so, you could make all calls in the U.S. and Canada for free. This plan was discontinued at the end of last year, but of course there are still a lot of people whose subscription has not yet expired. I seems that suddenly ALL calls made by people with this plan are being cut off after 5 seconds or so - quite a radical change, from "unlimited calling" to "say it in 5 seconds or lose".
Of course, Skype's non-existent "customer support" has nothing useful to say about this (or more often nothing to say at all), and the "experts" in the Skype User Forums are busily trying to blame it on the users, their computers, their ISPs, their pets and houseplants, or anything else. In the meantime, these users can't make any phone calls.
This is, unfortunately, typical of Skype service and Skype support.
Added: This is essentially a replay of what happened in January to the Skype users who had the Unlimited Calling Plan and switched to Skype Pro. They were unable to make any calls longer than 5 seconds, and it took weeks for Skype to fix it. Let's hope they do better this time. Hope, but don't expect.