The oppok9x phone cannot use wired headphones because it uses wireless communication technology and does not come with a 3.5mm headphone jack. oppok9x phones support Bluetooth headsets and Type-C headsets, users can choose to use wireless or digital interface headsets. This design can reduce the thickness of the phone and provide a better audio experience. Although the oppok9x phone cannot use wired headphones, it offers a variety of other options to meet the user's audio needs.