What is past is past.
That, in short, should be the determining factor for tense usage in that sentence. Since the action of calling the friend was done the night before, and the speaker is identifying himself as that caller, the action of calling and the attribution for that call should necessarily be both in the past tense: “I
was the one who
called you last night.”
Remember that structurally, that sentence consists of two clauses, “I was the one” and “I called you last night,” combined by the relative pronoun “who” (a subordinator) into a single complex sentence. Clearly, combining the two clauses would not in any way change the tense of either of them, so it’s out of the question that the main clause would suddenly take the present tense in the alternative construction “I
am the one who
called you last night.” That would be grammatically absurd.
That should also answer your question about the time referent for the two concurrent actions in that complex sentence. The tense will be same for both the main clause and the relative clause—the past tense in the case at hand: “I
was the one who
called you last night.”
However, there’s a particular situation that, in fact, calls for the use of the present tense—in
reported speech when the reporting verb is in the present tense, meaning that the speaker is making the statement right at the moment of utterance. We then can have, say, the following present-tense variations using different reporting verbs:
(1) “
I tell you that I was the one who called you last night.” (simple present tense)
(2) “
I’m telling you that I was the one who called you last night.” (present progressive tense)
(3) “
I’m saying that I was the one who called you last night.” (present progressive tense)
(4) “
What I am insisting on is that I was the one who called you last night.” (present progressive tense)
Note that in all such cases, the concurrent past tense of the reported statement—“I was the one who called you last night”—is retained. Be forewarned, however, that this is a special case that applies only to reporting verbs in the present tense. When the reporting verb is in a tense other than the present tense, the so-called
normal sequence-of-tenses rule for reported speech applies. This is now a different and more complicated grammar ballgame, though, and I suggest you check out and thoroughly study the following Forum postings on reported speech to get a solid grounding on the subject:
“Going back to the basic forms of reported speech”“How to use the normal sequence-of-tenses rule for reported speech”“Reported speech needs advanced grammar skills and a quick mind”
