I think we've been missing something really big in the timelines, or I missed this discussion and it hasn't been removed on our main timeline.
The text "no service in Yosemite" couldn't haven't come from GP's phone. According to the search warrant, the last communication from her phone was the 27th and it was NO LONGER OPERATIONAL. So there could have been no text on the 30th.
I stand by my theory that that GP's grandfather was calling during/after whatever transpired and BL was panicking and needed it to stop.
Edit: fixed spelling. Sometimes I swipe too fast and hit post in my excitement, so please ignore those blatant, nonsensical errors. Eventually I'll see them.