I tried to listen to a webinar from my iphone 11 using the app. Although I could listen the webinar though phone built-in speaker, I could not using wired headphones through lightning to 3.5 mm adaptor. If I'm watching a webinar on my phone, it's because I'm on the move and it does not make sense to listen on the speakers. (And please, don't tell me to spend cash on a new pair of bluetooth noise cancelling headphone)