Today, virtually no phone goes on the market without including an audio recorder capable of recording 3 to 4 minutes of your voice, typicalily for use as a dictation device.

The next obvious step is to let you assign these voice recordings as your ringtone. You could then record something like: "You've got a call" or even use your dog's barking. The Nokia 3100 and some Siemens phones include that function.