ɐ ɹᵻvˈɜːs tˈɛlᵻfˌoʊn dᵻɹˈɛktɚɹi ˈɔːlsoʊ nˈoʊn æz ɐ ɡɹˈeɪ pˈeɪdʒᵻz dᵻɹˈɛktɚɹi, kɹˈɪskɹˈɔs dᵻɹˈɛktɚɹi ɔːɹ ɹᵻvˈɜːs fˈoʊn lˈʊkʌp ɪz ɐ kəlˈɛkʃən ʌv tˈɛlᵻfˌoʊn nˈʌmbɚz ænd ɐsˈoʊsɪˌeɪɾᵻd kˈʌstəmɚ diːtˈeɪlz.
A reverse telephone directory (also known as a gray pages directory, criss-cross directory or reverse phone lookup) is a collection of telephone numbers and associated customer details.