Gotten several hangup calls. Calling back an automated message says "You've reached Michigan Voice, please leave a message." No response to message so far.
Only oganization I can find called Michigan Voice is an affiliate of the State Voices Nonpartisan Civic Engagement Organization. Normally I'd say they're political, but the calls only started after the election.
Also, while they use the name Michigan Voice, it's not clear if this is actually part of Michigan Voice or not - Michigan Voice is in a different part of the state, and their numbers have area code 517, not 313.