Who called from 31313131

when theey call i answere andnothing there when i try to  cll it back its the sound of a fax  machine

m recvng d call fr ds no.

this number call me but i fried to answer when i make searsh here it called me on my mobile

I found ithis nimber as a contact in my contacts list exactly after I installed "Nimbuzz" and it called me when I answered there was no reply and I recalled the operator system replied "This number is not used"

i also got a call from this number n tried callin it back. Who or wats number is this?