Campaigns rely upon both paid and volunteer phone calls to mobilize voters. Past field experiments show calls from volunteers to increase turnout and paid calls to be wholly ineffective. This article argues that the quality of phone calls rather than the presence or absence of a payroll explains this regularity. Three aspects of quality are considered: monitoring pace and interactivity, timing, and message. A fully randomized field experiment with over 100,000 subjects comparing professional and volunteer phone banks simultaneously was conducted during the 2002 congressional elections to test this hypothesis. The experiment discovers precisely the opposite relationship of prior research: effective professional phone banks and inefficient volunteer phone calls. The experiment also finds substantial temporal decay. The specific messages appear less important than tone or timing. The implications for the role of campaign consultants, replacing social capital, voter psychology, and the capacities of civic organizations are discussed.