You'll have to provide more information on what you're asking. Typically, all WAV files will be set in ulaw codec, unless you change the settings to be alaw. So record/edit all WAV files to be in the same format and you'll be OK.
It happens as part of the install, where you select the codec, that's all that needs to be done.
I just want to point out that after setting the codec for CVP there is no mechanism for converting the files to the proper codec in CVP. It is up to the person/process that uploads the files tot he CVP server to make sure they are in the right codec. Otherwise the user will not hear the file.