We rarely have folks who actually call in to the conference number on time. I usually have to call them on my cell phone and ask them to dial in to the conference number. My suggestion is to allow the conference call organizer to enter a phone number to call through the conference line. The automated call at the beginning of the meeting does not work because we don't always have the direct number of the person we are contacting (i.e., we have to call a secretary who then forwards us to the person we need to talk to).
Dial participants during conference call