Free conference call services in the U.S?

Hey people I was wondering if any one knows a free conference call service. I looked at some but some said you only pay long distance charges your carrier might charge. I'm confuse with that because I don't want to be calling Canada or something and having to pay that. I have long distance in the U.S any help would be appreciated.

As long as you have unlimited US long distance calling, using services like http://www.freeconference.com are free.