You may have accidentally enabled the Call Forwarding feature. Try dialing *73 and then Send from your phone. You may hear a couple brief tones and then the call disconnects. Then try calling voice mail *86 send. If that works, then have someone call your phone and don't answer to be sure it's routed to voice mail correctly.
If that doesn't work, you will need to contact customer care from another phone than yours but have yours handy for troubleshooting. 800-922-0204 or *611 from another VZW mobile.