If you've ever wanted your HD capable phones to play high quality music on hold, simply edit /etc/sipxpbx/freeswitch/local_stream.conf.xml.vm and replace all instances of <param name="rate" value="8000"/> with <param name="rate" value="16000"/> as shown:
/etc/sipxpbx/freeswitch/local_stream.conf.xml.vm
<configuration name="local_stream.conf" description="stream files from local dir">
<!-- fallback to default if requested moh class isn't found -->
<directory name="default" path="${service.docDir}/stdprompts/music/8000">
<param name="rate" value="16000"/>
<param name="shuffle" value="true"/>
<param name="channels" value="1"/>
<param name="interval" value="20"/>
<param name="timer-name" value="soft"/>
</directory>
#if(${moh.audioDirectoryEmpty})
<directory name="moh" path="${service.docDir}/stdprompts/music/8000">
#else
<directory name="moh" path="${moh.audioDirectoryPath}">
#end
<param name="rate" value="16000"/>
<param name="shuffle" value="false"/>
<param name="channels" value="1"/>
<param name="interval" value="20"/>
<param name="timer-name" value="soft"/>
</directory>
</configuration>
After that remove all old .wav files from /var/sipxdata/mediaserver/data/moh/ and copy the wav files from the freeswitch music archive http://files.freeswitch.org/freeswitch-sounds-music-16000-1.0.8.tar.gz. Once you're done with that restart Media Services in sipXconfig. The next time you are put on hold you will be listening to HD music on hold!