Meh, yes and no.
To make a true call faking app, the app needs to let you manuever through the rest of your phone while waiting for the incoming call, even interrupt whatever you're doing, like a real call would. I'm confused as to why this would require you to stay in your app. (Set an alarm for the chosen time that wakes up a Service that imitates the call.)
For the voice selections, I had -, M, F, or record your own. Huh? -?
See Call Faker (also, it's free) for what a call faking app should look like. It sets a timer that you don't have to see so people can even be looking at your phone and be fooled. It allows you to choose a contact that will be "calling you", even. And the incoming call screen looks like the normal one. Now that will fool someone!