Our company recently began using BB's. I do not have voice plan on mine, but some of my user's do. One user who has a 7290 model has asked how will she know she has a new voicemail? Does a message pop up on the general BB screen that she has a new voicemail?
There is no popup on the screen that indicates you have voicemail. You have to regularly check voice mail like you normally would. You can setup a voice mail number to dial in the phone options but that's about it.
On the 7290 (depending on your carrier) you'll see two things:
one, the little yellow telephone icon above the signal strength meter will indicate a missed call (as will your call log history) and there will also be a small icon that displays in the upper right corner of the screen that looks like an old "reel to reel" tape (two small circles connected by a straight line) that will indicate you have a new message waiting.
You 'might' get a calendar like even that says "New Voicemail Waiting" but sometimes I don't seem to get mine. Hope that helps
"For pretty things that serve no use, the true art finds its tether.
To those who know illumination comes wickless in the nether."
My 7250 on Verizon shows "Missed Call" (with the caller's number if it's not blocked) in the Messages display, and a separate message marked "Voice Mail" that I can open when I have any VM messages. The opened VM message shows if it's marked Urgent, etc. and also allows me to "Call Voicemail" as an option when you click the trackwheel while inside the VM message.
This may be carrier-specific. The feature is very helpful when you need to ignore calls for any reason, or when the phone's set on Quiet...my understanding is most of the 7xxx series BBs work this way so perhaps T-Mo has a similar setup. Good luck with your BB rollout!