iPhone dialing app for physically or mentally handicapped

My brother like some other disabled seniors needs a simple way to place or answer a phone call. I mean really simple, not what is now available that requires dexterity and thinking to use. Here’s what I want:

1. During app setup I will pick the number of buttons to be displayed on the screen. I could pick 2 to 10 buttons. For example lets say I select 8 for the button count. The buttons will be large and take up most of the screen area except for margins between the buttons.
2. One button will be a red “End Call” button. Each of the remaining buttons will be assigned to one contact.
3. The remaining 7 buttons (in my example) will each be programmed to dial the one contact I select from the Contacts list.
4. I will be able to lock or unlock the phone to display only the “Simple Phone” app by pressing a selected button pattern while I hold down the “Hang Up” button. The buttons will be numbered the way you would read a page, left to right then top to bottom, as a default. Or I could select the number assigned to each button and show it on the button in a small font.
5. The primary function of the buttons will be to display pictures of the people who can be called and to initiate a call to that person when a picture button is pressed and held down for a couple of seconds. I will be able to designate the length of the required button press during setup or alternatively I might chose to require a repeated press, for example two presses on the same button in succession would initiate a call.
6. I would be able to select a duration for phone calls. When that time has elapsed the user will be warned “Press any picture key to avoid an automatic end to this call”. The user will be given 30 second to push any picture button. If the user presses any picture button except the “Call End” the call timer will be reset.
7. There will be no other options for the user to avoid complications and confusion.