A conference call system comprising at least a gateway, a conference reservation agent and a multiport conference unit, can establish conference calls by calling conference call participants at a phone number specified by the conference call participants. When a user initiates a conference, an identifier is assigned to the conference and a URL referencing this identifier is transmitted to each conference participant. Upon clicking the URL, conference participants are presented with a web-form within which the participants can entered a preferred phone number and further join the conference. The multiport conference unit receives each participant phone number and calls the participants at that phone number. Upon establishing a telecommunication connection with each participant, the multiport conference unit bridges the multiple call legs to establish the conference call.