See: Headphone Jack (3.5mm) 2.5mm connectors are still common for TTY devices for the hearing impaired. Therefore most modern phones require a 3.5mm-to-2.5mm adaptor in order to connect to a TTY ...

Then all you have to do is plug the stereo 3.5mm jack into your in-flight ... for which you'll need an adaptor (or a lot of patience in getting the stereo 'band' to sit across the right section ...