Android Voice Mail

We transferred our phones from another carrier to T-Mobile a couple weeks ago. We brought our Android phones (and numbers) with us. We have been unable to access voice mail since then. Before, we would just press and hold "1" for a moment, and it would bring up the voice mail menu. Doing that now causes the phone to dial *86, but then I get the message that "this call cannot be completed as dialed." I know I've gotten voice mail messages, because I've gotten text messages that are an attempted transcript of the message. These messages invite me to dial a phone number (469 area code) to listen to the full message,  but it's a different phone number every time. Also, it's not a voice mail account or menu -- I can just listen to that one message, then choose what to do with it, but as soon as I delete the message, the service hangs up on me -- I can't do anything else. What am I missing?