The old codes continued to work in parallel with new codes until January 1970, when the "ANN: All-figure Numbers Now" advertising campaign prompted callers to use only the new codes.
ðɪ ˈoʊld kˈoʊdz kəntˈɪnjuːd tə wˈɜːk ɪn pˈæɹəlˌɛl wɪð nˈuː kˈoʊdz ʌntˈɪl dʒˈænjuːˌɛɹi nˈaɪntiːnhˈʌndɹɪd sˈɛvənti, wˌɛn ðə "ˈæn: ˈɔːlfˈɪɡjɚ nˈʌmbɚz nˈaʊ" ˈædvɚtˌaɪzɪŋ kæmpˈeɪn pɹˈɑːmptᵻd kˈɔːlɚz tə jˈuːz ˈoʊnli ðə nˈuː kˈoʊdz.