Headset being placed in jack cuts off the speaker - Standard industry practice. Per Standards group ANSI C63 - Already being addressed by industry. Already common in many phones including world's smallest mass market cell phone. Subpart D - Compatibility Sec. How the requirements are met.
Infrared port allows activation of all features remotely.
Only software protocol needs to be added. No cost to use standard signal levels. Keys do not require contact with human body to work. Dished keys make it easier to press keys for people with limited manipulation. Headset jack is a TTY connector - Headset jack already used as TTY connector today for some TTYs.