Is it permissible for a fiancée to speak with her fiancé over the phone or via email to discuss non-essential wedding arrangements, and does a phone call constitute khalwa (private seclusion)?

The suitor is a stranger to his fiancée until he concludes the marriage contract with her. Therefore, he should not see her, nor should she see him, except out of necessity and in the presence of a mahram. Speaking over the phone does not constitute khalwa shar'iyya (unlawful seclusion), but it is preferable to forgo it by speaking with the wife's family instead. If communication or messaging occurs, it must be appropriate, far from being overly soft in speech or anything unbefitting, while emphasizing that she is still a stranger to him. Speaking with her over the phone or messaging is permissible as long as there is no fear that it will lead to something forbidden; otherwise, the door must be closed.