I just found the coolest phone ever "OwnFone" (you can google "myownfone" to find their web site). It only has a couple of buttons on it, that you can program with a name and the phone number. This would be PERFECT for my dad, as he is beginning to forget how to use a cell phone.
It looks like this is only available in UK. I would love to know if anyone knows of a similar phone that is available in the US.
Super simple. Depending on how bad he is, you can also just program his autodialer, my dad can't actually remember our numbers anymore, but he can just pick up his phone and hit 5 and send, and it will call me (4 is my mom, 6 is my brother).
If you have a cellphone yourself, you can also contact your provider (local office is usually best) and explain the situation. They may know of a perfect phone for him, one he can just say who he wants to call, or have it preprogrammed and easy to use for him.
Currently, he can still answer his phone and he regularly wears his roadID bracelet (with my phone number). I have told him he can ask someone to dial my number on the bracelet for him, when he wants to call me.