Didn't answer, but they left a blank voicemail containing call center noise in background.  Caller ID said Unassigned.  

Likely spam/solicitation/telemarketing call.

Another poster mentioned they were soliciting for donations to Children's Miracle Network.

Multiple calls, "Unknown" caller ID, no message.  Likely telemarketer.

Blank voice mail.

I rec'd a call from this number bit did not answer. The caller did not leave  message

Left no message.  Caller ID showed "Unassigned".  I'm not answering any call that I don't know.  Good luck robodialer!