Changing from using to getting clean can be a scary transition for an addict. It's the first time in a long time they will have to deal with the demons of their addiction and face real life. Remember, she has been numbing out reality by using.
As far as the phone... in my opinion, I wouldn't pay for it nor would I let her have it in her possession. This is a time they need to focus on themselves and the less distractions (even from us co-addicts) is the best. I had to learn that my ABF's recovery is about him. In time, I will have my time with him and work in family therapy to repair the relationship.
I agree with the above poster, take this time to step back and let the adjustment take place. Take a moment to look at why you feel the urgent need to help, step in and rescue. This is part of co-dependency.
Hope this helps. Much prayers to you as you go through this. I know the feeling all too well.