In the AddaLine app, you have the option of listening to voicemail if people leave them.
1) Open the AddaLine app > press Conversations
2) Press the conversation with the number / contact that you have missed a call from
3) In the bottom of the conversation there should be a voicemail recording. You can press the play button to play the voicemail. Make sure the volume is turned up on your device. Voicemails can be listened to from the dashboard as well.
If no voicemail is found, make sure that you haven't disabled voicemail.
To verify that, follow these steps:
1) Open the AddaLine app > press More > press My numbers
2) Select the correct AddaLine number
3) Verify that the Voicemail is enabled
You can of course record your own custom voicemail greeting if you want to. Press here to find out how to do that.