Despite higher hit rates for cell phone samples, inefficiencies in processing calls
to these numbers relative to landline numbers continue to be documented in the U.S.
literature. In this study, we propose one method for using cell phone provider
information and Internet resources for validating number status. Specifically, we
describe how we used ‘‘in network’’ options available from three major providers’
web sites to determine the validity of cell phone numbers. We tested differences in
working number rates (WNRs) among valid and nonvalid numbers against a normal
processing control group and determined that the WNR among valid numbers was
approximately 14 percentage points higher than the WNR of the comparison group.
This process also shows promise in reducing the effort required to determine
working status and may provide a basis for developing screening tools for cell
phones that capitalize on resources that are unique to this technology.