How can a wife be convinced of the danger and impermissibility of "innocent relationships" over the phone with the opposite sex, especially since her husband is silent and unwilling to change?

"What your friend is doing is from the steps of Satan; she must stop it and repent to Allah. You should advise her gently and kindly, and provide tapes that discuss the seriousness of this matter. Islam has forbidden any relationship between a man and a woman except on the basis of a legitimate marriage. If the husband knows about his family's relations with non-mahrams and remains silent, this is dayouthah (pimping/cuckoldry), and Allah will not look at the dayouth on the Day of Judgment, as stated in the Hadith (definition). However, if his silence is due to his nature or he knows nothing, then there is no sin upon him."