Davina wrote:

So, this bit is more like chess than the pill-swallowing bit. Sherlock sent a text (well John actually but you know what I mean) which the cabbie might think was from the dead woman, who is not dead (in theory). BUT Sherlock is pretty sure that the cabbie knows that he has made a mistake with the pink overnight bag and that, in fact, the text is not from the woman but from whoever has found the bag. The cabbie goes to the arranged meeting place, with a fare on board. There Sherlock realises the fare isn't the murderer and the cabbie sees it is Sherlock Holmes who has sent the message. The assumption is that the cabbie has been made familiar with what Sherlock looks like courtesy of Moriarty and probably he also tells the cabbie where Sherlock lives.

The thing that is puzzling is, why should the cabbie keep the woman's pink phone? I have some ideas but I want to see what the rest of you can make of it first.

I think that the whole set up, with the forced suicides etc. were designed solely to get Sherlock's attention, with the cabbie being used as a fall guy.

He keeps the phone because it is a direct link to Sherlock now, he KNOWS that.
Yes, he realised his error of driving off with the bag because that linked him to the woman.
Remember now that he is reporting back to Moriarty, the more deaths he orchestrates, the more money he gets for his kids. As things progress ( the slip up  with the pink suitcase; the phone that has been planted in his cab ) Moriarty quickly realises that Sherlock will be on the case and as his #1fan, he decides it is time to lure Sherlock into this game & watch what he does with it.
So undoubtedly, Moriarty would have advised the cabbie to keep the phone as bait for Sherlock.

It's not so much that the cabbie was the fall guy in the first place, but as the game changed so to did Moriarty's plans.

To Black-out means to Pass-out or faint. She's saying that she must have fainted at Lauriston Gardens which (of course) is a lie.

It always makes me laugh when John says "you blacked out?" thinking Sherlock is talking about himself.

If the cabbie got that message, would he think that something had gone wrong and for some reason the girl had survived?

If the cabbie had stuck around to see Jennifer Wilson (almost wrote JW, but realized that could be John Watson), he would have seen her scratch the clue on the floor. Of course, maybe that would have been OK with him, if he and M were trying to lure Sherlock. I don't think he could've known it was the e-mail password, though.

As for how he ended up with the phone, Sherlock, of course, thinks Jennifer "plaunted" (sorry, love the way he says that) on him, but where, when, and how? Wouldn't the cabbie notice a strange cell phone in his pocket? I suppose she might have left it in the cab if she realized early enough that she was being abducted. Maybe it was in the suitcase and the cabbie kept it when he through the suitcase out. (But who keeps her phone in her suitcase?)

Anyway, I assumed the cabbie didn't realize he had it till John texted him and it buzzed or rang.  If he did know before, he might have kept it (a) to lure Sherlock or (b) as a sick souvenir.

I'm just speculating as I go along here. I don't really have a theory all in place.