T46 How to create a High Quality Ringtone with Sox or other

Hi, i found an mp3 which i have converted in wav with Audacity.

when i run the wav with an player he has a good quality.

But when in convert it with sox : sox InputFileName.wav -e u-law -r 8000 OutputFileName.wav

even with -c 1, when i put it on the phone, and even if it do more thank 100kos, it worked, but we have a bad quality and sizzle .

What is the best way to create a good quality ?

thanks