Yes I agree you don't need to solve his problems. I just mean for the purpose of the response to his argument, simply reminding him that there are other ways to contact her and she will have the phone back on xx date.
But... to play devils advocate I wonder if you might think about working towards co-parenting more. Maybe set aside some time to discuss what consequences would be that you both can live with, and under what circumstances they would be given.
This is easy for me to say, though I am not at all following this advice, and actually dreading a time when I have to deal with my daughter as a teen.
Of course, on the other hand, you could say, I'm sorry you feel that way. Those other suggestions don't really work for me but thanks for offering them. She will have her phone back on xx and please let me know if there is an emergency.
And don't give it/his complaint another thought. ..
