What is the ruling on money remaining in a payphone that operates with coins and does not return the change to the user?

If someone leaves a small amount of money behind due to inability to take it, the money remains their property. This amount must be given to its owner. However, if the owner is unknown, then the money must be given in charity on their behalf and spent for the benefit of Muslims. In Islamic law, something unknown or impossible to recover is treated as non-existent. This is supported by the hadith of Ibn Mas'ud, who gave in charity the price of a slave girl whose seller he could not find, and by the hadith of the man who wrongfully took from the spoils of war and then gave it in charity on behalf of the army. Based on the noble verse: "So fear Allah as much as you are able," money whose owner is unknown should be spent for the benefit of Muslims, and charity is one of the greatest forms of this. This includes all money whose owner is unknown, such as usurped property, borrowed items, and deposits.