IS-95's variable rate voice coders reduce the rate being transmitted when speaker is not talking, which allows the channel to be packed more efficiently.
ɪz nˈaɪnti fˈaɪv vˈɛɹɪəbəl ɹˈeɪt vˈɔɪs kˈoʊdɚz ɹᵻdˈuːs ðə ɹˈeɪt bˌiːɪŋ tɹænsmˈɪɾᵻd wɛn spˈiːkɚɹ ɪz nˌɑːt tˈɔːkɪŋ, wˌɪtʃ ɐlˈaʊz ðə tʃˈænəl təbi pˈækt mˈoːɹ ɪfˈɪʃəntli.