On reflection, I have perhaps been complicating and confusing matters by referring to the narrator as "unreliable".
I agree with Andrew Brown that, contrary to what I said, the narrator is not exactly contradicting him- or herself by saying, or reporting others as saying, both that the young man has no desires (for his birthday) and that he wants to escape his world.
More centrally, the narrator is only reporting the views of others. He (or she) is not asserting that the young man was "incurably deranged in his mind". He is merely reporting, accurately, that the parents were "confronted with the problem of what birthday present to bring a young man who was incurably deranged in his mind". They are confronted with this problem simply because the doctors have told them, and they have accepted, that the young man is "incurably deranged in his mind". They are confronted with this problem whether what the doctors say is right, wrong, or undecidable -- as long as they themselves accept what the doctors say.
Thus the issue, for the parents and for us, as readers, is whether we should accept unquestioningly what the doctors say. This is not a speculative or obscure point to speak of as "the issue", because it is quite explicit in the "surface" story: the parents become festive when they start thinking of a plan that does not unquestioningly go along with the doctors. The father explicitly says: "To the devil with doctors!"
This does not, of course, necessarily mean that he has decided his son is "curable". But he appears to have decided at least to have faith in "mere possibilities of improvement", to quote the story. He has decided to be "responsible", to quote him himself, rather than just go along with what are presumably the doctors' recommendations.
This is all so simple and virtually undeniable as to appear, perhaps, not very interesting: to "trivialise", as someone said, the story. But it only does so if one regards "mere possibilities of improvement" as trivial. They may appear less dramatic and absolute than a hypothetical other-worldly afterlife love-in of father, mother, and son. But is it not at least arguable that it is precisely such a happy-ever-after afterlife solution that trivialises the tragedy?
I get the distinct impression that participants in this discussion think my proposal that the boy himself may be making the third telephone call is a kind of deus ex machina appeal to miracles, whereas Dolinin's afterlife hypothesis is no more than sound common sense.
Surely this odd state of affairs has arisen because of an unquestioning faith in what is not even asserted by the narrator, but merely reported by the narrator as, by implication, having been asserted by the doctors: namely, the boy's "incurability".
And even if the doctors were right that the young man would never become free of delusions, why would that preclude "possibilities of improvement", such as his at least deciding he would like to come home again and his parents' deciding they would like him home, even if advised against this by the doctors?
Would it not be a small, ordinary but extraordinary, (from my point of view as a psychotherapist) entirely believable and realistic, "miracle" if the parents and their son had, more or less at the same time, come to glimpse a "mere possibility of improvement"? How wonderful, if the son of whom they had despaired, should actually sense that now would be a good time to telephone them. Some small change in their relationship might ensue. He might even be able to live with them again, or perhaps just enjoy without terror his birthday present.
Is it not believable that Vladimir Nabokov would enjoy setting this "chess problem" in which readers, as it were, lose their "life current" between the "two stations" (of the Cross they are preparing for the young man?) of the only two possibilities they contemplate for the third telephone call: (1) the girl still not having taken in what the mother explained about her misdialling, but thereby dialling three ominous sixes which surely, to symbolically fixated readers, tell of doom; and (2) the hospital telephoning to report doom directly?
The mere fact that the narrator speaks of the train losing its life current "between two stations" should, as I said earlier, alert us to something. Why not just "between stations", as in Eliot's "East Coker", unless we are supposed to reflect on the "two"? Multiples of two preponderate in the obtrusive arithmetic of the narrative.
There is a nice symmetry in that, while the boy allegedly attributes human agency to inanimate nature, readers are not merely guilty of a similar Pathetic Fallacy, as Brian Boyd long ago suggested, but, more fundamentally, under the spell of the hearsay "incurability" suggested by the very first sentence of the story, are unthinkingly attributing a lack of human agency, non-agency, non-humanity to the boy.
Is it a mere accident that readers are doing this, or is it the result of the supremely intelligent human agency of Nabokov in preparing this trap for readers to fall into and then learn from?
Anthony Stadlen