I think you have to decide what your situation is and "how much" phone you want your daughter to have.
We likely won't get our son a cell phone until he can pay for it. This is because A. we have a landline and B. his school is a ten-minute walk away.
I grew up mostly walking to and from school--mostly alone--(or taking the bus) and coming home to an empty house. I'd call mom when I got home. I wasn't to call her again at work unless my siblings didn't arrive home or the house was burning down. This is the opposite of how we raise our children now, with constant checking in.
I also think it's good for older kids to have situations where they need to make decisions for themselves. It's good for them to learn how to ask other adults for help when necessary. It taught me to take "common sense" chances when I needed help. I had opportunities to learn that the world is not a scary place, but that many people more or less do want to help each other out. I was never hurt or scarred emotionally because of those interactions or situations.
Statistically, the world isn't any more dangerous than it was back in the day. Too much phone and helicopter parenting makes for kids who literally can't think for themselves as adults.
But it is situational. If you choose not to get a landline, get a phone which has the features/limitations that you want. Talk to her about using it responsibly.
Personally, what I get upset about when I see younger people with phones is more that the phone becomes a way to disconnect from one's immediate surroundings. The more gadgets (games, internet, texting) there are on the phone, the more kids --and adults-- get sucked into them instead of being present. I've seen a frightening increase in adults handing over their phones to increasingly younger children to play with, usually to entertain the child or get them out of the parent's hair. I think kids miss out on their parents and on their real, physical world when we make this a habit.
And Molly, if you think your daughter needs it, what you propose sounds very reasonable.