Is a girl considered married to a young man if she tells him "I marry myself to you" over the phone and he accepts, then she wants to leave him and insists that the marriage is invalid without a guardian to get rid of him?

"A marriage contract is not valid merely by the-woman's offer and the-man's acceptance without a guardian or witnesses, according to the majority of scholars. Therefore, what transpired between the girl and the man is not considered a marriage. If it was a doubtful contract, she may follow the opinion of the Shafi'is, who state that a corrupt marriage does not require annulment or divorce, because it is an un-contracted marriage."