I have yet to hear a cell phone that matches the quality of a land line. I can tell when someone is calling on a cell phone, even when I am using a land line. The sound quality just is not there.
I think I am particularly sensitive to sound quality, since I have very bad tinnitus. I hear a constant loud high-pitched screech of two or three simultaneous frequencies; if the sound quality is at all lacking, it is difficult or impossible to understand what the other person is saying. I think that people who do not have tinnitus can probably compensate for the lower sound quality on cells without too much difficulty and may not even notice it.
Speaker phones are difficult to understand, for pretty much the same reasons.
I can’t stand it when someone calls me on their cell. The sound is all wonky. They’re always losing signals. What’s worse is they never say to hold on a second while they talk to a cashier or someone in front of them.