Is she? She doesn't act to change her fate; she's a passive observer in her own life, which seems to make whatever consciousness she has epiphenomenal at best (and therefore something we'd feel justified in assuming away under Occam's razor, since it has no effect on the world outside her head).
And at the risk of going all postmodern, it's worth pointing out that she is in reality a character in a story and therefore not conscious. One could argue that the point of the story is that characters in a story are not conscious (and go from there to a paradox: since we all tell stories of our lives, can any of us be conscious? But I think that doesn't offer anything that's not already present in the argument that we can't have had free will in the past since our past decisions are now fixed).
Yes, Louise is a character so she cannot be truly conscious, but that's too meta. You could go post-post-modern and argue that since Louise's real name is Ted Chiang, and he is conscious (surely?), then she must also be :)
I suspect that making a decision to seek out a phone that works and placing a call to a phone number you never had access to counts as a conscious effort, rather than being the behaviour of a mindless automaton.
If knowledge of the consequences of an action means taking that action is no longer the act of a conscious being, then what you are suggesting is that people who plan ahead are not conscious.
Vague "efforts to steer her daughter away from climbing" are the Greek-myth workaround. Surely Louise could have told her that she knew specifically that she would die on this trip, this date...
In the story, it is implied the ability to see the timeline all at once, non-sequentially, comes with the loss of free will. It's a different mindset where people think they are play-acting rather than choosing the future. Of course we find this puzzling -- after all, we think sequentially :P Louise didn't warn her daughter because it wasn't in the "script" of the future.
My point is that if she made a meaningful choice to make the phone call and find out the term "non-zero-sum", as manicdee was claiming, then surely by the same token she also made a meaningful choice not to warn her daughter.