Which companies provide which VoIP services in The Netherlands
(consumer ànd business market)? (In a possible answer the following
catagories could be distinguished; 1.) Peer2peer VoIP companies and
Services (e.g. Skype, MSN); 2.) VoIP services offered by companies who
do not have an infractructure of their own (like Vonage in the US);
3.) VoIP services by telecom and cable companies who already have an
infrastructure (KPN, UPC) and 4.) ViFI (VoIP over WiFi) companies and
Services.

www.skype.com is undoubtedly the best VoIP system so far, IMHO.  I use
it all the time both the free Computer to Computer and the inexpensive
Computer to Phone called SkypeOut that starts with a 10 Euro deposit,
enough for HOURS of calls.  You can call to anywhere in the world!
Remember it is NOT where you are calling from, but where you are
calling TO that sets the rate.  More than 30 countries at about
US$0.02/minute and many more for just a few cents more.  New and more
economical agreements are always coming up and the service gets better
and cheaper all the time.  Before, your unused credits on SkypeOut,
the Computer to Phone service, expired in 180 days, now it is 6 months
from the LAST time you used SkypeOut.  The software is great and easy
to use, you can chat, talk, play, pass files, etc. and with a Cable or
DSL Modem it sounds like calling next door.  It is truly the wave of
the future in communications.