How do I find my Sprint user ID?

Hello, all. My coworker just bought a pearl yesterday with Sprint, switching from a WM Smartphone. On her old phone she was set up to retrieve emails. She asked me to try and set up her BIS email for her, and when I tried to create a new account on the Sprint BIS website, it said an account already existed for her phone. I chose the option to have the password sent to the phone, which I received. The only thing is my friend does not know her user ID. How can we get this? Does Sprint set up some kind of default user ID, or is this something she would have set up when using her WM phone? Sorry to be asking so many questions, I did search the forums to no avail. I appreciate any info anyone has to offer!

Go to Setup wizard. Check under Personalization. Now you have what you are looking for.