Android - How can I disable voicemail notifications?
The only thing that worked for me is to stop the Phone Application. It restarts itself again, so you don't have to worry for missing calls or anything.
Steps:
- Settings -> Apps -> ALL -> Phone.
- Click Force stop
Source: Clear Voice Mail Notification Icon
I am in the same boat as you. Since I found no way to actually disable voicemail notifications on my Nexus 5, I instead configured the longest possible voicemail greeting the T-Mobile system would allow, which consists of complete silence for 3 minutes. I have not gotten a single voicemail notification since.
You can install and configure T-Mobile's own Visual Voicemail app. You will get notified about your voicemails through it instead of the system's Phone/Dialer app, with the ability to dismiss that notification. As a bonus, you can also listen to and delete your voicemails without having to dial in and waste prepaid minutes.
Be aware that this app needs to be able to send and receive one SMS message in order to enable its functionality. If you are using Voice+ feature of CyanogenMod custom ROM, you will need to temporarily disable it.