An initial data center is selected to host an online conference. This data center can be selected based on the geographical locations of the participants. Typically, the data center closest to the centroid of the participants is selected. During (or before) the conference call, an ‘effective’ centroid is calculated based on effective distances. Effective distances are based on a combination of the physical distance between a participant and a data center, and an effective distance factor (or weighting) that is based on one or more of the participant's device/driver type, the participant's network type, the participant's connection type, and a participant weighting factor.