Why can't I hear my voicemails?

There is a known issue where some users have reported not being able to hear voicemails. It relates to the data connection you have and whether or not the voicemail is "downloaded" on the client. 

If the app is having a hard time getting connected, the voicemail will not be full downloaded and cannot be accessed to listen to. Try toggling on and off airplane mode for your device to reset your data connection, and if you aren't already on a Wifi connection, connecting to Wifi could do the trick.