All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
All perfect praise is due to Allaah, Who blessed that young girl with repentance. As long as she has repented of that sin; which is having a relationship with a foreign man and practicing sex with him over the phone, Allaah Almighty accepts the repentance of the one who repents to Him if he gives up the sin, regrets doing it, and resolves not to go back to it again. It would be better not to tell her husband or anyone else about what she did. That is because Allaah Almighty likes that the slave conceals his faults.
What that girl did does not incur corporal punishment; however, it is included in the Zina (adultery/fornication) of the tongue and ear that is to be expiated from by repentance.
Allaah Knows best.