I have an unlocked iPhone 6 Plus and I had been using it on T-Mobile since getting it. Last week, I switched to Tracfone and now when I am checking my voicemails, the keypad keys don't seem to do anything. For example, pressing 7 to delete a message or pressing 6 to save a message. No matter what key I press, nothing happens. Not sure if this is an iPhone issue or a Tracfone issue. Has anyone run into this problem before or know of a fix?