DUI three years ago. Driving on a restricted license 2 months later. On probation. Sent a threatening voicemail message to an ex. Is that a violation of probation? What am I looking at time wise if it is?

Depends on the exact words in the Message. Actual threats of violence is called Terrorist Threats and if threats of death were included, can also be a felony. So yes depending on what you said, it can be a violation