Good morning nonny! Actually we do see Sherlock calling Mycroft in THoB, which is interesting in it’s own right–when Sherlock first breaks in to Baskerville, Mycroft texts him. He knows Sherlock prefers to text. In turn, when Sherlock wants something from Mycroft, he calls, having previously stated in TGG that Mycroft is only texting because he’s had a root canal, that it must have been quite painful. This is a really subtle way of showing the audience that although Sherlock and Mycroft are often posed as being at odds with one another, they do have a solid understanding of each other and can communicate effectively.
As to Sherlock standing on the roof calling John–oh, my giddy gosh goodness, you have hit on my favorite personal theory of all time.
I don’t think John was meant to be there.
Sherlock had particularly crafted a reason for John to not be there–the phone call stating that Mrs Hudson had been shot. Obviously Sherlock is behind this because if Mrs Hudson really had been, he would have totally freaked out a la ASIB Sherlock-CIA Smash. So the only reason John is even at the scene at all is because he got to Baker Street, saw Mrs Hudson, and immediately understood Sherlock was going to do a bad thing.
I think Sherlock’s plan was actually for John to be at Baker Street in order to 1) not be in any way involved with the danger Moriarty posed; and 2) to offer protection to Mrs Hudson and the flat. It was not news to Sherlock that the people in his life were being threatened, because Moriarty left the IOU clues. If John had been any less focused on Sherlock, he would have got to Baker Street, and being a soldier, would have basically done a perimeter check (I still can’t believe he didn’t do something like this) seen the incredibly fucking obvious handgun the assassin had in the toolbox in her front foyer (please Mrs H in the future can you please let Sherlock vet your handymen) and he would’ve been tipped off.
But Sherlock misjudged John.
Sherlock did not plan on John being so in tune, because at this point our dear Sherlock is a little clueless to the potential reciprocation of his feelings. I don’t know that Sherlock knows what he feels for John, but he does know he feels something. It’s on his face in the scene at the foot of the stairs in ASIP, it’s on his face repeatedly through TBB, the pool scene in TGG, the deduction sequence in ASIB with Irene whispering in Sherlock’s ear (pls he only has eyes for impressing John yet again), and then we have THoB, in which Sherlock admits that John is special to him. But they’re friends, and only friends. In THoB, while Sherlock is reaching some zenith of frustration with their relationship as it stands, John actually pulls away, even cruelly so. Instead of being impressed with Sherlock’s deductions to Henry at 221B, John rolls his eyes and basically asks if that’s necessary. His conversation with Lestrade about Sherlock’s supposed aspberger’s, which by the vast majority of clinical literature Sherlock does not have, others Sherlock and places him firmly in that category of “freak” which is well known to Lestrade. He refuses to see Sherlock’s panic attack for what it is and instead takes it personally. When Sherlock apologizes, John accepts his apology and fails to validate their friendship by offering a reciprocative statement–in fact, his acceptance is so stoic that Sherlock continues offering praise–John’s fantastic, he’s a conductor of light–until John tells him “don’t overdo it.”
So this is Sherlock’s mindset going into TRF, which is exacerbated by John’s comments to him in the car on the way to the trial, in which John is essentially telling him to behave himself. Lestrade, taking Sherlock in to interview the young girl, tells Sherlock to be, you know, not himself, which seems to validate John’s “opinion” (Sherlock’s interpretation) of Sherlock being in some way fundamentally flawed. Eventually, Sherlock brutally uses this to his advantage by refusing to care about the faked news of Mrs Hudson being shot.
But the audience, having seen the majority of s1 and s2 from John’s perspective, I believe is being told that John is essentially in love with Sherlock and is totally aware that he is in love with Sherlock. We are repeatedly told that John’s in love with Sherlock throughout TGG and especially ASIB, but at the end of ASIB John is torn–is Sherlock in love with Irene, or is Sherlock incapable of love at all? He says so to Mycroft, more or less, that “Sherlock doesn’t feel things like that, at least I don’t think.” I’m paraphrasing but you feel me. So John is pulling away from Sherlock because he doesn’t think Sherlock will ever reciprocate those feelings, which gives us trash can THoB/TRF John.
But Sherlock only sees the trash can. He isn’t looking back over the big picture. So when he sends John away from Bart’s, Sherlock thinks John will take care of things at home and not return to Bart’s because he doesn’t think John cares about him in any way deeper than flatmates and friends. But John does! John, although he’s been trying to pull away, is definitely still in love with Sherlock and Sherlock is his priority even when there’s a potential threat to Mrs H.
So John goes back to Bart’s. We see that John’s sniper has to locate a position and set up, in contrast to Mrs Hudson’s and Lestrade’s potential killers who are already well placed during this time, so it’s logical even to suppose that the sniper has been tracking John through the city, from Bart’s, to Baker Street, to Bart’s again.
Sherlock is not prepared for John. He doesn’t want John to come any closer because he doesn’t know where the sniper is, but if the sniper sees Sherlock survive the fall John will certainly die, and the sniper is looking at John, not Sherlock. I believe that any elaborate plan to set up a fall would have been set up and orchestrated for the benefit of the CCTV, which Mycroft would have been controlling. If the CCTV were all pointed up, watching Sherlock, he could have jumped, it would have captured the first 3 stories or so of the fall, and then there would have been an explainable and non-suspicious lapse before the cameras panned down to see Sherlock dead on the pavement. The fall itself literally only exists to provide some kind of footage, incontrovertible proof that Sherlock really did die. Now I’m not sure I believe the story Sherlock told Anderson in TEH but it’s beside the point. Whatever is going on in front of Bart’s, outside of the CCTV frame, cannot be seen by John or John won’t believe it.
So Sherlock needs to stop John in his tracks, so he can’t do anything but call. And it’s heartbreaking. Sherlock cries real tears, which and highly unlikely to be any kind of act considering John couldn’t really see it. He reaches his hand out, as though caressing John’s image on the pavement. He lies through his teeth and doesn’t do a particularly good job of it–even John doesn’t believe him.
In terms of Sherlock preferring to text, he would also prefer to do a lot of things. Stay with John, for one. Not lie to John, for two. But he can’t do the things he would prefer. And he has to call.
And right before he jumps, he throws his phone away behind him onto the roof. Throws his heart away.
There is no reason for John to be at Bart’s when this happens and every reason for him not to be (if you put aside, obviously, the element of dramatic storytelling in a television show). John does not, at this point, have to see Sherlock die in order to believe he is dead. With Molly and Mycroft both to identify the body and confirm his death, with a death certificate, with CCTV footage of the first 3 stories of fall followed by a body lying bloody on the pavement, with a funeral, etc etc etc there is no reason for John, without witnessing his death, to disbelieve the facts as Molly and Mycroft tell him. On the other hand, John being at Bart’s throws off Sherlock’s entire plan. What if John’s sniper WAS in a position that he could see that Sherlock had survived? What if John had not listened when Sherlock told him to stay put and instead had been in position to know Sherlock wasn’t dead, which would have also potentially given his sniper reason to know Sherlock wasn’t dead?
The only thing about this whole scene that suggests Sherlock planned for John to be on the scene is the bicyclist, but I think he was just intended to be a back-up plan just in case someone–LITERALLY ANYONE–walked onto the scene that wasn’t supposed to be there to help cover up Sherlock’s survival. It wasn’t that the bicyclist was aiming for John at all. The bicyclist was aiming for anyone who might have rounded that corner unexpectedly. That’s it.
SO. Long story short, the phone call was unplanned, just like Sherlock falling in love with John was unplanned. Inconvenient, to say the least. Complicates things. Makes it so much harder for Sherlock to leave. All that.
And Sherlock, with his incorrect interpretation of John’s pulling away, would not have realized that John would be so affected. I genuinely believe Sherlock thought, when he returned that John would not be that upset because he didn’t think John would have been all that upset when he died. He thought that John would be like oh cool trick! wow! He thought, oh, it will be like any other friend, but John instead mourned like a widower. He was totally broken. This consistent miscommunication and misinterpretation takes us all the way through TSoT and HLV, where John becomes aware of Sherlock’s feelings and where Sherlock, still failing to recognize those same feelings in John, again sacrifices everything so that John can have what John presents himself as wanting, whether or not that’s really truly what he wants in his heart of hearts.
Expect to see a great deal more phone metaphor in the future, friends. Personally, I think ultimately Sherlock will become aware of John’s feelings for him through a text. Probably an angry, heat-of-the-moment text, and then there will be all this romantic tension as they become aware that they are in love with each other and then have to wait to actually physically be together.