Who called from 2536480228

this is the first time receiving a call from this number.
Nobody said anything.

found number on my cell phone today as a missed call

this phone number called my gfs phone twice, she said they were silent and then hung up, when called back they dont answer goes straight to vm.

called me  when i answered they had hung up. tried to call them back but the call failed

calls up to 12 times a day, but when I pick up they don't say anything.... Who is this?