No, fraud is basically lying, cheating and stealing - knowingly using your address (and her name) to apply for a cell phone account is misrepresenting her address to the phone company. Why? Won't the bills be coming to your home address (with her name?) The only answers that make sense is that she is worried that her home address has been flagged by creditors OR she is opening an account that she wants to hide from someone at her home address. Either scenario doesn't play out well for you.
Your options: tell her to immediately cease any further attempts or you will report her for attempted identity theft. It IS a former employer, right? She probably has access to all your other personal identifiers (including Social Security Number, Date of Birth, etc). Be smart and order credit reports on yourself to ensure that she hasn't already opened other accounts using your name/data.
If she doesn't stop, follow up with the phone company and your local police. Good luck.
This is a general comment to your posting and is not meant to constitute legal opinion or advice. This posting does not establish an attorney-client relationship in this matter. If you think you need legal advice or representation for this matter, you should consult a licensed attorney in your jurisdiction.