This number came up on my phone did not answered it but was wondering what it was for.Called it back and a recorder came on and said it was an invalid number. what could it be.don't have time for junk.would like to know who it was from and what they want.

This  number '31 29' just tried to called me, (at 8 PM) but I didn't answer. Yesterday it was the number '31 17' (calling at 4 AM) and four day ago the number '31 28' (calling at 8 AM) -I'm sure they are connected, because all of those numbers are very unusual in my country! (Denmark) I can't say why they keep calling, since I never answer to such strange numbers!