I remember when cross-oceanic long distance calls required both parties to shout as loud as they could into the phone -- and often still not be heard well enough to make out what they were saying.

Modern IP telephony often has very high quality voice reproduction (my wi-fi to wi-fi Fi calls sound fantastic), in exchange for some timing issues. Echoes usually get solved in software (usually), and dropouts seem to be the main complaint.

In exchange, my wife can call her family in South Korea for approximately nothing, using the same data backbone as we use to watch movies and read web pages.