Over the past decade, the U.S. telephone system has undergone rapid change, with changes in the size of the universe of numbers and how they are assigned. The rapid growth of cellular phone usage is another key development and is the subject of this paper. In February 2004, a supplement to the Current Population Survey on telephone service was conducted. Questions address the prevalence of different types of telephone service in households and how these services are used. This information is of critical importance to developing efficient telephone survey methodology in these changing times. This paper first discusses the questionnaire development process and the quality assessment activities associated with the supplement instrument. Estimates are then provided of the percentages of households with land-line only, no land-line but wireless service, both land-line and wireless service, and no telephone service. The way households use these services is also examined. Demographic profiles of households with these characteristics are presented. This information can be used to assess the potential bias in estimates from surveys depending on the telephone sampling design used.