Its not a scam people, its from university of walden or any other oversea university you might have registered or you was linked to. You can pick up the call and listen without talking at first then when the person at the other end talks then answer and they will tell you about the requirements to studies oversea without paying anything.
No it is not a fraud, University of Liverpool provides education online, this is the webiste for the online programmes http://liverpool.ohecampus.com/, http://www.liv.ac.uk is the University's campus website but the online programmes will also be listed there. The Enrolment office for the o line programmes is based in The Netherlands, hence the reason for +31 code.
Both websites are valid just as the number. The University of Liverpool delivers online programmes, for which the website is http://liverpool.ohecampus.com/ , Liverpool Online Higher Education Campus. You will also find the same online programmes listed on the University's campus website, http://www.liv.ac.uk . The Enrolment and student support office for the online programmes is based in the Netherlndas, hence the reason for +31 country code. The office exists and is there for anyone who has done their research properly and wishes to visit.