I was looking for a way to convert wav files to alaw files and had trouble finding the right software to do this so I tried using sox but got some strange errors when converting to alaw
After playing around a bit I found a workaround by converting to gsm format first using sox and using Asterisk to convert gsm format to alaw next.
Let me explain how:
1. Upload your wav file to your server and make sure you put it in a directory the Asterisk user and group have access to.