Nokia 6270

I have a weird issue. I have the 6270 on t-mobile and whenever I check my voice mail, I receive a blank text message. Whenever someone leaves me a voice message, the VM symbol does NOT appear, but I receive a blank text message. It's really more of an annoyance than a major problem, but its burning up my text messages. Of course I called t-mobile and they don't want to help with the 6270. Any of your help would be greatly appreciated.