ɹᵻvˈɜːs tˈɛlᵻfˌoʊn dᵻɹˈɛktɚɹiz ɑːɹ jˈuːzd baɪ lˈɔː ɛnfˈoːɹsmənt ænd ˈʌðɚɹ ɪmˈɜːdʒənsi sˈɜːvɪsᵻz ɪn ˈɔːɹdɚ tə dɪtˈɜːmɪn ðɪ ˈɔːɹɪdʒˌɪn ʌv ˌɛni ɹᵻkwˈɛst fɔːɹ ɐsˈɪstəns, haʊˈɛvɚ ðiːz sˈɪstəmz ɪŋklˈuːd bˈoʊθ pˈʌblɪkli æksˈɛsəbəl lˈɪstᵻd ænd pɹˈaɪvət ʌnlˈɪstᵻd sˈɜːvɪsᵻz.
Reverse telephone directories are used by law enforcement and other emergency services in order to determine the origin of any request for assistance, however these systems include both publicly accessible (listed) and private (unlisted) services.