Skype is now offering free outgoing calls to any land line in North America.
"Skype is a little program for making free calls within the US and Canada to all phones until the end of the year. Skype to Skype calls anywhere in the world are also free. It's easy to download and use, and works with most computers."
What is really nice about Skype is that it was easy to traverse the school districts firewall to make long distance calls. Nothing fancy to do, I just dialed out. (+1 area-code then the number) It seems to work over port 80, the same as internet traffic. The call display, comes up with skypes phone numbers, so by default it has an added call blocking feature.
I was able to do a five way conference call, with the other four people using their cell phones. It worked very well, although the sound was a little tinny at times. I can't complain though, since I wasn't paying a cent for it.
There are other offers like VOIPstunt but Skype seemed to work the best through my districts firewall. If you want to test Skype out, my alias on Skype is "qdsouza".