Softphone interface using React

I am looking for someone to assist me to build a web based interface using React for a softphone used to establish voice calls through a browser. The size of this should be responsive. Width is generally fixed, estimated to be about 200px, height is about 400px but may span the length of the entire page. Elements should be centered. It does not have to be functional in the sense that it does not need to be able to actually make the calls. Instead, I am just looking for a frontend interface with some placeholders that will allow for javascript functions to be added in at a later time to perform the necessary functions (i.e. perform the actual call). Essentially, the softphone would look something like the dialer on an iPhone and provides transitions across various different interfaces. For example: 1. Start with a login screen 2. After login, show the dialpad 3. When on a call, hide the dialpad and show call controls (mute, hold, add participant, etc) Some mockups are attached. I am looking for documentation to be provided as well to allow for easy customization for color, where javascript code for each element, transition, etc are to be located.