Nick,
Do you have firmware RVV114EN?
In the PPS, in Tab F, where you put the "Cap Code" information in, make sure you've selected the correct Tone alert. Do not set it to Alert by Zone.
If you are using your own audio tones, pick a music tone, and write to the pager. Once you have written the pager's programming, hit the "Music Alert / Voice Prompt Programming" button on the very bottom left. From there, load in your audio file.
Unication has a tutorial on this and I've copied it to my dropbox. Here is the link
https://www.dropbox.com/s/wvzrsprldtok9pi/00-G1 wav File Configuration v2.docx?dl=0