Not once have I heard my friends complain they get strange calls and messages, apparently they were from spammers, in fact, it`s my problem too, I`d say it really irritates when you get something like that, I`ve found this site
http://cellphonetrackapp.net/ and now I`m gonna advise them to check it out, you may visit it yourself it you need to find a good app for blocking strange incoming calls!