I keep getting blank messages from this number too.  They've called me 3 times today.  I wish they'd stop!

ndp leadership robocall

Better not be friggin' robocalls!

It was an automatic poll asking, if you were to vote today, which NDP candidate you would choose. The called me 4 times in as many hours (apparently not an anomaly).

Called four times in four hours, each one hour apart. Left blank voice mails every time.