bɪkˈʌz ðɛɹ ɪz nˈoʊ sˈɛntɹəl dˈeɪɾəbˌeɪs ʌv sˈɛl fˈoʊn nˈʌmbɚz, ɹᵻvˈɜːs fˈoʊn dᵻɹˈɛktɚɹiz ðæt klˈeɪm təbi fɹˈiː kænˈɑːt ɹᵻtˈɜːn ˈækjʊɹət ˌɪnfɚmˈeɪʃən ˌɔn ðoʊz nˈʌmbɚz, ɔːɹ tˈɛnd tʊ ɪŋklˈuːd ˈoʊnli pˈɑːɹʃəl dˈeɪɾɚ ɹᵻlˈeɪɾᵻd tə ðə fˈoʊn nˈʌmbɚ səbskɹˈaɪbɚ.
Because there is no central database of cell phone numbers, reverse phone directories that claim to be free cannot return accurate information on those numbers, or tend to include only partial data related to the phone number subscriber.