Via Cool Tools:

“free conference.com’s Standard Services Are Free

Our Web-Scheduled Standard and Reservationless Standard conferencing services are free, but we do not provide toll-free (800) Dial-in Numbers.  Although some callers may be local to our Dial-in Numbers, most callers should expect to dial a long distance number to access our conference bridges and, therefore, pay only the normal domestic long distance rates charged by each caller’s long distance carrier for the length of time they are on the call.”