Free spam call blocker

Someone has called me twice lately from this number. As I don't expect any calls from the UK, I did some research on it. This number is not registered to any name in the UK. The number is provided by O2 mobile provider and the phone is currently located somewhere in the EET time zone (eg.: Romania, Ukraine, Etc,) not in the UK. I also called international directory enquiries and they told me that 11 other people have already asked them for this number. I must assume this is a scam / robocall