Telephone Number Portability and the Prevalence of Cell Phone Numbers in Random Digit-Dialed Telephone Survey Samples

Abstract

Telephone number portability is a feature of circuit switch telecommunication networks that allows people to ‘port’ (i.e., permanently move or transfer) a telephone number from a landline to a wireless service, between two wireless services or, less frequently, from a wireless to a landline service. It was introduced in the United States as a means of improving competition among telecommunications companies and offering customers greater flexibility in telecommunications services (FCC, 2006 ). The problem for survey research is that telephone numbers thought to be landline numbers within a particular geographic area are sometimes later found to be associated with cell phones, which is problematic for more traditional random digit-dialed (RDD) telephone surveys that tend to exclude cell phone numbers. Number portability is occurring globally, with regulations varying across countries. Singapore was the first to introduce number portability in 1997. Number portability is also provided in the European Union, as well as in countries such as Australia, Brazil, South Korea, Argentina, Colombia, and Taiwan. Canada, India, Japan, and several other countries have plans in place to offer number portability in the near future (Rembert, 2006 ).