Companies will do anything to get people to call anywhere. “Free conference calls” that require calling somewhere in Iowa for example, may be free to you
(if you have nationwide calling plan which most do), but not to your provider who pays a nice connection fee to the local network operator in Iowa. Do it often enough and your own provider will do whatever it can to get even with you (Sprint tried, but lost in court to block calls to these free conference call numbers), up to and including terminating your service. Know who you are calling before calling them.