It isn't really an issue they can fix. Voicemail and missed call notifications come in from carriers over specially formatted messages. You'd need to develop a new out of band messaging protocol that is as reliable as SMS delivery and get all the 30+ carriers Apple works with globally to roll it out before they could turn off the old stuff.
Why does it have to be out of band? Couldn't they just append a signature or something?
I guess I misunderstood - I thought he was saying he tried to contact them but they didn't reciprocate.
hmm yeah but i wonder what they had to say about it
My guess is: "Yes, we know about it, we had an engineer spending X amount of hours actually implementing this feature".