Is it an ACN telecommunication company you are talking about? Cause one of my best friends is working there as an HR manager and she told me that sometimes they have to make almost a hundred interviews per day to find the right candidate. So maybe you didn't receive a call back from them because you forgot to remind them about yourself? When you're applying for a job in such a large company it's better to send them a thank you letter. Like, thank you for the opportunity, hope to hear from you soon, etc. I've read about that in
this article. It might be useful for your future interviews.