You can do what you request with a custom app. You can use the Asterisk Playback command to play the sound file.
If you don't wish to write any code you can use an IVR with no choices defined. You will need to rename your sound file to usergreetingnnnn.ttt, where nnnn is a unique 4 digit number and ttt is the recording type (wav, gsm, ulaw, etc.)
Create an IVR and select your usergreeting as the sound file. Set the IVR outcome to Hangup and don'r select any key choices.
Kind Regards
S