I also just got a missed call from +38681897034 on my irish mobile sunday 27th 01:30am and found this forum, I gnerally don't call back if I dont know the caller, if its important they call back again or text :) good night
Also had a missed call from this number at 0200am. Also got a fright and didn't know who t was. Also foud this forum and am happy that I am not the only one.