According to T-Mobile, third party voicemail services don't work on Monthly 4g. I got my MyTouch 4G on 'FlexPay' and visual voicemail worked then. Later, after getting a bunch of messages from T-Mo saying that FlexPay was being phased out and I had to switch to Monthly 4g, the voicemail system operated like my old T-Mo Nokia candybar phones. I soon tried to use the Youmail app, but never got it to work. Youmail says that it may not work with some pre-paid plans, which may be how they see StraightTalk on the network.