If you want to get a proper file for the voice prompt, to reduce the codec
ffmpeg -i welcome.wav -ar 8000 -ac 1 -acodec pcm_s16le fixed.wav
Then to cut the file it is good this one
ffmpeg -i fixed.wav -t 48 -c copy inbound-welcome.wav
First edit analog trunks
Configure Outbound Routes
In the Main Trunk of the outbound rule set the fxo-1
Create a custom voice prompt in PBX Settings - Voice Prompt - Custom Prompt
Creates an IVR in Call Features
Setup a inbound route
The config like this
