I have also seen this method fix voicemails that are not playing and not deleting, too. A quick reset of the voice app does wonders and takes two seconds.
On the app, click on the "Sound" icon at the lower left part of the tool and select "Microphone." Then, open your voicemail service on your phone and play the voice message. The online audio recorder then clicks the "Record" button on the audio recorder while the voicemail is playing. If you are recording using an external mic, make sure that your phone is on the loudspeaker and pointed at the mic.

I called customer support. They were not able to fix it and made it worse. Now it rings once instead of three times. They put in a service request and said it would be 1-3 days. Now they say 3 to 5 business days. I don't understand how something so simple could be such a major problem. I just wanted them to change the number of rings to at least 7. Disconnected the 1st of the junction boxes at top of door. Phone line rings after doing this so proves problem is in the home. I then ran a new wire pair to the NTE5, problem then came back, even with the pull out isolation port or whatever it’s called. Then wired direct to the back plate if that’s the correct term, phone starts ringing again.
Along with these features, InstaVoice uses a new voice-to-text transcription engine, to transform all your voicemail to text messages. To save your voicemail, use the backup feature provided with the software. Through InstaVoice's 'ReachMe' option, you can connect to a WiFi that lets you send and receive calls even without a SIM card.