Annotated VoIP Links
NOTE: NetComm is NOT responsible for the contents of external links.
Session Initiation Protocol [SIP]
White Papers (in .pdf) on SIP, an excellent summary from Network Computing, and a useful collection from Ubiquity Software.
SIP Centre is dedicated to the SIP Protocol. The Basics article provides a very concise intro to SIP.
This article contains a summary feature comparison of H.323 and SIP protocols
General VoIP Info
As far as general information sources go, check out the VoIP WIKI site.
A site called Packetizer has a lot of info on H.323.
Notable VoIP Companies
Include
Vonage the Broadband Phone Company.
Skype was invented by the folks who thought up Kazaa and is generating a lot of publicity. Virtual phone service.
Engin is a local offering that has bundled VoIP services with their own ATA equipment.