Head to the website, create an account, get your FreeConference account and you can FreeConference away.
It really is that simple.
Nothing to download to use the conference call facility, just dial the number you are provided and enter the access code. Give the participant code to those you want to dial-in and, just like that, you are on the call.
I have had one participant complain of the call fees but I call this number all the time on my mobile and cannot see that I have noticed vast sums being charged to connect.
We are a three office business, with offices at either ends of the UK - this easily connects us at any time, no notice required.