rolf wroteCould be spam or something like that. There are ways for people to falsify the originating number, I think. Also, could be a call routed over international VOIP, sometimes they send bogus Caller IDs. Most common is 00000 but I guess they can send anything.
Okay, sounds a reasonable explanation. It might be a call via Skype! I totally missed that one.
Thanks for the hint Rolf ;)