Gimme your VOIP links!

I’m researching VOIP options and Vonage looks rather promising as I haven’t a clue what acronyms like SIP and NAPTR stand for, but SIPthat.com is a “blog on SIP, VoIP, IP Telephony and all that is IP communications” and has already increased my knowledge somewhat.
Thankfully murble on #linux pointed me at FWD which looks very promising!