Mobile phones are employed as an assistive platform to improve the living quality of individuals who are deaf. However, deaf individuals experience difficulties using existing functions on mobile phones. This study identifies the functions that are inadequate and insufficient for deaf individuals using existing mobile phones. Analytical results were referenced by designers to optimize mobile phone functions for the deaf community. A simulated mobile phone interface, the PeacePHONE, was designed to evaluate functions. Functions were developed based on the conceptual design of a multifunction mobile phone. This conceptual design was based on the daily life requirements of individuals who are deaf. PeacePHONE usability was tested by 18 deaf individuals. Five factors were assessed: user experience profile, user perceived usability, functions on existing mobile phones that should be retained, new functions that should be added to existing mobile phones, and functions that are most useful to individuals who are deaf. Positive and negative feedback on the PeacePHONE is presented as well. (Contains 3 tables and 5 figures.)