Is it permissible for a man to speak with a woman who is not a mahram to him over the phone or to meet her without a chaperone?

The fundamental principle regarding speaking with a non-mahram (definition) woman is prohibition, unless there is a necessity or need, while adhering to the Sharia (definition) guidelines such as absence of suspicion, avoiding a soft and alluring tone, and limiting the conversation to the extent of the need. The husband should be advised that excessive conversation with non-mahram women beyond what is necessary is impermissible, and arranging to meet them is not permissible if it necessitates being alone with them, because being alone with a non-mahram woman is forbidden by scholarly consensus, due to the Prophet's (peace be upon him) saying: "No man is alone with a woman except that her mahram is with her," and his saying: "Indeed, no man is alone with a woman but Shaytan is the third of them."