[BHSPitMonkey]

There's still the issue that you have to answer your phone with this service (provided you don't write an Android app that automatically answers calls from this number and puts them on the loudspeaker). Once I get used to knowing the phone call will happen every day, I'll just start holding the pillow around my head until the ringing stops and return to sleep.

I'm much more tempted to write something for a Raspberry Pi with speakers attached that will immediately begin yelling at me at the proper time. More configurable, and less prone to weird phone-related issues. (The only vulnerability would be if I started unplugging the device or speakers in my sleep, but there are ways to mitigate that.)