I think my whole premise was off. I forgot about the 4 minute phone call at 7:12. The phone clearly wasn't dead before 7:08. Do you mind if I delete my comment and your responses so I don't confuse people? Thanks for them though.
The time on that text message is curious, though.
There's a 1 minute call at 6:53 and another at 6:54, both from Trayvon's phone to North Dade, and maybe they're to W8, then an incoming call at 6:54 which goes on for 18 minutes, which puts it ending at 7:12, and I assume that it was from W8, as I assume the 4 minute call at 7:12 was from her. She's on a carrier that uses the T-Mobile network, so those calls show as "in network".
There's a 1 minute call at 7:04 which comes from outside the T-Mobile network, which I assume was Chad and that Martin did the "call waiting" thing to talk to him real quick and then went back to the 18 minute call.
So why, 4 minutes after that "call-us interruptus", and 4 minutes before the end of the 18 minute call, would W8 be texting to Martin? Can you even send a text from a cell phone if you're in the middle of a voice conversation on it?
(I have a "non-smart" cell phone, and I'm old)
Like I say, I assume the 18 minute call was from W8, because the "sheltering from the rain at the mail thing" supposedly happens during her penultimate call, and she doesn't indicate that long a gap between it and the final call.