I downloaded this file which is a set of spanish sounds for freeswitch: 

http://files.freeswitch.org/freeswitch-sounds-es-mx-maria-44100.tar.gz

As you see It only has sounds for the 44100 frecuency. 
To generate files for the 8000, 16000 and 32000 frecuencies,  I untarred the file inside freeswitch/sounds directory. 

After I untarred the file, there was a directory called es/mx/maria which has all this subdirectories: 

ascii
currency
ivr
phonetic-ascii
voicemail
conference
digits
misc
time
zrtp

For each of these subdirectories I made this:

cd "one of the directories inside sounds/es/mx/maria "
mkdir 8000
mkdir 16000
mkdir 16000

cd 44100
for a in *.wav;
do
     /usr/bin/ffmpeg -i "$a" -ar 8000 -ac 1 -ab 128 "../8000/"$a;
     /usr/bin/ffmpeg -i "$a" -ar 16000 "../16000/"$a;
     /usr/bin/ffmpeg -i "$a" -ar 32000 "../32000/"$a;
done

Now I have a complete set of spanish sounds for the 8000, 16000, 32000 y 44100 frecuencies

¿What would I need to configure in freeswitch to use these spanish sounds instead of the english ones?

Thanks in advance for your kind help.