17 Reasons Why You’ll Love the iPhone 6

Excellent Call Quality

VoLTE is also good for something else: High quality phone calls. If you enable VoLTE on your iPhone 6, you'll be able to place calls over your high-speed LTE network. This, in turn, will lead to more natural sounding conversations between friends, family and co-workers.

This doesn't sound like a huge feature but it is if you spend a ton of time talking on the phone like we do. Again, this feature is not available on older iPhones because they don't support VoLTE. If you want to make high quality phone calls with the iPhone, you'll need the iPhone 6 or iPhone 6 Plus.