Is it permissible for my husband to speak on the phone with his maternal cousin's daughter to greet her, and what are the Shariah guidelines for that?

It is permissible for a husband to speak with his female cousin (daughter of his maternal aunt) to check on her, provided that the Shari'ah guidelines are observed. This means the conversation should be for a specific need, without the woman softening her speech or the man deriving pleasure from it, and far from joking or excessive laughter. The cousin is a non-mahram, and it is not permissible for her to be lenient in her speech with him. Rather, the conversation should be limited to extending greetings and inquiring about her well-being, as well as the well-being of her parents and children, after which the call should be ended. This should only occur when there is a need.