Is it permissible for a wife to speak with her family over the phone without her husband's knowledge if he unjustly prevents her from doing so?

A husband does not have the right to completely prevent his wife from speaking with her parents, especially if they are not causing corruption, as that would be an endeavor to sever ties of kinship, which is forbidden. If the husband fears their corrupting influence, he may prevent her from the extent that causes corruption, but not from all contact. Therefore, there is no blame upon the wife for speaking with her parents without her husband's knowledge; rather, it is obligatory upon her if they are in need of her asking about them and speaking with them.