ðɪ ˌɛstˌiːdˈiː kˈoʊd zˈiəɹoʊ wˈʌn wʌz ɐsˈaɪnd tə ðə lˈʌndən tˈɛlᵻfˌoʊn ˈɛɹiə ˌɔn sˈɪks ˈeɪpɹəl nˈaɪntiːnhˈʌndɹɪd fˈɪfti nˈaɪn æz pˈɑːɹt ʌv pɹˌɛpɚɹˈeɪʃənz fɔːɹ səbskɹˈaɪbɚ tɹˈʌŋk dˈaɪəlɪŋ.
The STD code 01 was assigned to the London telephone area on 6 April 1959 as part of preparations for subscriber trunk dialling.