Is a girl sinful if she makes her voice harsh or rough when speaking to men over the phone or directly, to avoid fitnah, and is that considered imitating men?

It is recommended for a woman to speak harshly when addressing foreign men, in order to cut off covetous desires and prevent those with sickness in their hearts from coveting. Her voice should be natural, without softening or making it tender. Al-Baghawi, Al-Qurtubi, Ibn Al-Jawzi, Ibn Adel, Abu Hayyan, and Al-Alusi mentioned this, based on the Almighty's saying: "So do not soften in speech [to men], lest he in whose heart is disease should covet, but speak with appropriate words."