Can the contents of a phone call recorded without permission be used as recording evidence?

To state the conclusion first, it is not illegal for one of the parties to a call to record the conversation with the other party.

Article 3(1) of the Protection of Communications Secrets Act prohibits wiretapping or secretly recording the conversations of others, and a violation of this may result in criminal punishment.

However, recording done directly by a party themselves does not fall under this.

The Supreme Court has also ruled that "it is not illegal for one party to a telephone call to record the contents of the call with the other party."

Therefore, as in your case, recording after inducing the other party to state the fact of the debt while you yourself were on the call is not illegal, and that recording can be recognized as recording evidence in a civil suit as well.

However, because it can become a separate problem if it infringes the other party's personal rights or if the recorded contents are disclosed, it is best not to circulate that recording evidence outside the court and to use it only for the trial.

In addition, the recorded contents must be composed so as to be directly related to the legal issues, and to reduce the room for an unfavorable interpretation in court, the advice of an expert is essential.

Please note that it is advantageous to prepare recording evidence for use in actual litigation strategically, together with an attorney, from the collection stage.