What should a woman whose voice is naturally soft do if she is compelled to speak with a man who is a stranger to her (neither her husband nor a forbidden degree of kinship), whether directly, over the phone, or via the internet?

If a woman knows that her soft voice may be a source of temptation for men, she should coarsen it when speaking with non-mahram (definition) men. As Imam An-Nawawi and his companions mentioned, emphasizing that a woman's voice is not awrah (nakedness), but it is forbidden to listen to it if there is a fear of fitnah (temptation). She should not answer with a soft voice. She must observe all the Shariah regulations when addressing non-mahram men, whether the conversation is direct or through intermediaries.