If you have already upload mp.3 recording or enabled and write Text to Speech. Then next step is to set call routing.
Click on top right on app, when side panel opens click on call routing.
Here you can select. Call or VM
Call : once you choose this option, caller will hear your IVR greeting then App will ring, you can take call and talk to caller.
VM : If you are going for a meeting or not able take calls, you can set this option. Callers will hear IVR greeting, then they will hear VM instructions, they can leave voicemail.
You will get notification in App, You can listen to recording within App.