I didn't experience with the site you mentioned.All websites are look like legitimate .So it is hard to tell whether it is safe .If you are not sure or have any doubts whether the website can be trusted then exit from the site and take your time to investigate further into the website.To check a site is legit or not  you can check user reviews, feedback, problems, responses and rating about the site by the Google search.To check the website is secure more information can be provided by website Webutation.net  .Get the "whois" information from Whoisxy.com to know the administrative contact, technical contact etc.

Did you mean the network unlock..? .If it so means you can unlock your Nokia by getting lock code for lumia 920 mobile from the provider Simpleunlocking.com  . You can get the instruction to unlock your mobile from Mobileunlockguide.com .

To check a website is scam or not, secure more information can be provided on government websites such as Fakechecks.org  which is created by the National Consumers League. For checking this while logging onto websites to any server, always look out for “http” which will be on the URL bar on the top of the screen.Check the reviews and feedback of the site in Google.com .To check the site is legit or not check its "whois" information from the site Whoisxy.com