I'm an internal employee (technician) who wanted to shoot for the next step up technically (System Performance Engineer) and decided to give it a shot. I was given a chance despite the fact that I'm still pursuing my degree (I have 9 years of wireless experience). The phone interview was roughly 30-45 minutes and I was invited to a face-to-face with a panel of 3 people. Panel interview was tough but fair, roughly 1.5 hours technical and 1 hour behavioral.