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:
<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, browse to System >> Servers >> <server_name> >> Media Services and then click Apply. sipXecs will ask you to restart Media Services, do so at your convenience. After you restart media services, the next time you are put on hold you will be listening to HD music on hold!