That's really interesting. I thought of adding another one where I asked not only is it sex, but is it adultery? But I was a little worried about people getting bogged down in legal definitions (which vary by country/state0.
With the phone sex, I definitely consider it sex, but my rationale goes thus:
Phone sex is either two people pretending to have sex with each other while masturbating, because they can't have physical interpersonal sex due to distance
It's two people pretending to have one kind of sex with each other while having another kind because they can't have physical interpersonal sex due to distance.
Now, this presumes that they're not just choosing to have phone sex because that's what they want to do at the time, as blue_braces
points out, but I'm okay with that presumption because I think it's the most common circumstance. And it seems more like the second one to me.
Of course I could do a whole poll on phone sex. One interesting wrinkle is: have they had physical sex before? As an example, in my fiction Scott and Logan have phone sex while Logan is off on a mission, having an established sexual connection already and referencing specific times they had sex and specific sex acts during the phone sex. Jean-Paul and Adam, OTOH, have phone sex before they meet in person. Is one circumstance more likely to be deemed sex than the other? I think for some people yes. I think someone who would count phone sex with a lover traveling on business as sex might still say "we haven't had sex yet" of someone s/he had only had phone sex with. Although in the J-P/Adam case I think he'd be more likely to say "We haven't met yet" and not even mention the phone sex :-).