Error : Music on hold


I downloaded mp3 file and convert it to wav(PCM, 16bit,8000Hz) and tried to

upload it on “Music on Hold” module. but it gives me following error

Error Processing: “sh: mpg123: command not found
sox: Can’t open input file ‘/var/lib/asteriskmoh/orig_Excuse_Me_Sir.wav’: No such file or directory” for Excuse_Me_Sir.mp3!
This is not a fatal error, your Music on Hold may still work.

can anybody help me