This paper describes a study of the effects of four types of content presentation for consumers waiting on-hold to speak to a call center agent. Of particular interest was the interactive voice portal (IVP) condition in which callers used a voice portal to retrieve news and other information while they waited on hold in a queue. An experiment explored the effect of four content types (Silence, Music, Advertisements, and Interactive Voice Portal) on callers' estimates of on-hold duration across four hold intervals (60, 120, 240, and 480 seconds) and for three customer tasks. The dependent measures were hold-time estimation error and customer satisfaction ratings. Each participant placed four calls to a simulated call center in which they were presented with one of the four content types and hold durations. Both Content and Hold Time had a significant effect on estimation error and customer satisfaction. The interactive voice portal yielded the best results overall, suggesting an interesting new approach to call center hold queues.