At the beginning of 2016, the ACS implemented a design change for the Computer-Assisted Telephone Interview (CATI) data collection mode. Prior to 2016, the ACS had been acquiring telephone number data for sampled households from several third-party vendors. In a cost-saving effort, the ACS decided to let these contracts expire and begin using internal resources to receive telephone number-address matches from the Center for Administrative Records Research and Applications (CARRA). In addition to phone numbers, CARRA agreed to provide an associated score and rank for each telephone number, to enable ACS to target the numbers with the highest likelihood of successful contact. This design change was fully implemented with the January 2016 panel for February 2016 CATI calling. The purpose of this research project is to analyze the results of this change to the ACS CATI program in terms of interview responses, the relationship between CARRA model scores and contactability, and contact center labor productivity, for the first two months of CATI calling following the switch to CARRA telephone numbers.