Recently I switched to the Belgacom for TV, movies and internet but I hardly use it for phone calls.
Skype has stepped in with crystal clear calls. I use it for calling family and friends. The quality of the line is excellent.
For more details, click here:
http://www.skype.com/intl/en-us/homepage
It is great for work. I used it for a one hour skye to skype call to Australia in the early morning. The line was excellent. It did cut out once, but a 60 min conversation for free is good value in my books.
The instant messaging service is great and it allows clients to ping me a quick question when they need a quick answer.
It would be useful if there was a phone that you could use with skype. It seems they exist in the US but they are not making this available in Europe yet.
I have yet to test calls skype to mobile or via mobile. If any one has experienced this, let me know how it went.