You're just emulating phone calls. The problem is dropped calls. The networks are unreliable. We need a packet-switched network where the bits just flow. And we need to design applications for which a very low bit rate is acceptable.
Email is the great example.
The ability to get your email both in and out is satisfied by a very low bit rate, because when you write a message and click send, you don't have to wait for it to be translated into something else. It matters when you're navigating. When you're on an Internet access service, the time from when you click on something to when you get that next screen has to be just a few seconds. But that can happen on a very low bandwidth connection, because each screen is really small. In one respect, it's a shame that the screen's are small.