[linkinpark875]

How come calls on FaceTime audio sound much crisper than phone calls? Been loads of advancements in phones like 4G but the "HD call" has never come as many peoples phone voices so sound different.

[InfamousTeal]

HD voice does exist, but you need to:

1) have a compatible phone, most modern ones are fine
2) be on 3G (or 4g which will fall back to 3G)
3) be calling someone on the same network as you, who also has a compatible phone and is on 3G
4) not be on O2

... Super simple !