Being stymied from discovering any hard facts to back me up, I have a suspicion -- a mere suspicion -- that one change at my end might bave caused the improvement in SkypeOut call quality.
In December 2007 I moved my prime Internet connection from Optus cable, with a nominal maximum 256 Kbps upload speed, to Telstra BigPond's new high-speed cable, which my testing has shown to consistently run uploads at over 1 Mbps.
My purpose in getting the BigPond cable was for the much higher upload speed, so that I could offer the occasional interactive web demonstration of my software product NotesTracker (if you're interested, via IBM Lotus Sametime Unyte which has probably the best rates available for such a service). As an aside, I've retained the Optus cable connection, because it's a most reliable service that I've been using since its early days and their download allowance and rates are better that BigPond's. (What else would you expect? I feel that Telstra's technology is outstanding, but their asking prices are generally too high: maybe by 30% to 40% for cable (although this pales in comparison with their hyper-usurious PAYG rate of $2.00 per MB for casual excess mobile phone usage).
Anyhow, back to SkypeOut QoS for Australian calls. These days, I'm far more satisfied with voice quality than I was last year, and drop-outs are few and far between. I reckon that the quality is now approaching that of regular landline-to-landline calls within the mainland states and territories and Tasmania. (I've never tried calling external Australian territories, but last week I did make a SkypeOut call to Mauritius and that sounded okay.)
Finally, I have a little tip for SkypeOut users (or regular Skype PC-to-PC calls, for that matter). For a few days last week, my callers kept asking me to speak up and I couldn't fathom out what was going wrong. Finally I twigged to the fact that I have just started using Dragon NaturallySpeaking for voice recognition, so that I can write iTWire articles more readily. In doing so, I had been fiddling with Windows and Skype speaker and headset settings, and had inadvertently turned off Skype's setting for automatic adjustment of microphone level:
As soon as this auto-adjustment was switched back on, the problem went away. The obvious moral is, don't fiddle with this particular Skype setting.
So there you are. I plan to keep on using SkypeOut and not any other VoIP service. It's quite good enough for my purposes, but your requirements and expectations might differ so "your mileage might vary" as they say.
The only other aspect of SkypeOut that I need to decide upon is whether to stay with the original Skype Pro offering, or upgrade to one of the recently-introduced "Unlimited Country" or "Unlimited World" plans. Are they any better? And what does Skype mean by "unlimited" I wonder. My analysis of these will be in a forthcoming iTWire article.