Poor voice quality isn't limited to cell phones. I've found that with VoIP phones in quiet locations. The voice can break up. There is still nothing better nor more reliable that na real POTS phone. That's why I keep it won't get VoIP phone. POTS phones always work.
We've had an interesting regression in the quality of telephone communications. Just when crystal clear wired / fiber connections started to spoil us, wireless cellular phones came along. In public places the most common mobile phone conversations that I hear are "What, What? I can't hear you." It seems the combination of very low fidelity, tiny speakers with poor volume, and the high ambient sound levels conspire to thwart smooth communications. Even in quiet venues with respectable signal strength, the other end of the line sometimes sounds like a voice scrambling device. I'd love to see the return of high quality telecommunications. Surely if we can have mobile video conversations we ought to be able to engineer a simple reliable audio connection.