I was initially contacted by a recruiter within Halliburton, calling to arrange a phone interview. We conducted the phone interview within a week or so. I was contacted a few days later to arrange an on-site interview. I attended the on-site interview at the main campus a few days later. I sent thank you emails to all 3 interviewers the next day, then waited.... I emailed HR for an update a week later, and got no response. I called her a week later, left voicemail, and got no response. Wrote it off as a loss. Two months later, received email from hiring manager saying they used an internal candidate. I believe I was a "filler" interview, and that they had intended to hire from within all along. This has happened a few times to me so far. Very frustrating.