What should I do about a girl who calls me, sometimes before Fajr, telling me she is about to pray Fajr, and should I talk to her or not?

A man's communication with a woman he does not know, for no need, is suspicious. Speaking with her is not permissible except out of necessity and assurance against temptation. If a man fears temptation from his conversation with her, he must sever his relationship with her, because the temptation of women is not limited to sight; sometimes the voice can be tempting. If he desires to marry her, he should seek permission from her guardians and propose to them, and she remains a stranger to him until the marriage contract is concluded.