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.