The five minutes phone call makes this claim dependent of duration. What happens when you allow 10 minutes time?
In the original paper Turing mentions 5 minutes.
>I believe that in about fifty years'time it will be possible to programme computers, with a storage capacity of about 10⁹, to make them play the imitation game so well that an average interrogator will not have more than 70 per cent, chance of mating the right identification after five minutes of questioning.