Originally Posted by
nmenaker
but, and I have no idea why this is, the european GSM networks ALSO sound better than the USA GSM networks. It never ceases to amaze me, that I can take my SAME phone to europe and plug in a european SIM and boom, get much better voice quality than anything I have ever heard on a USA GSM network.
I believe European carriers tend to use the full rate codec while AT&T tends to use the half rate one in order to conserve bandwidth. T-mobile US tends to use full rate.
Many phones let you force full rate - if you have AT&T, check your phone model for how to force full rate and see how it sounds.