BH.....when my W moved out I continued to pay her cell phone bill for about 2 months. I then told her that I was no longer going to pay it and it was one of my personal boundaries. She asked me if she could give me money for it and I told her "no" that I did not want to be responsible for anything that has to do with her apartment. She looked at me weird but put up no fight. With that said we did have a financial agreement in place between the both of us when she moved out that would provide enough money for her to pay her own bills.
I refused to pay it but I put her in a position to make it happen due to our financial arrangement when she moved out.