Straightforward phone interview with internal HR for 30 minutes - this is a preliminary screening to identify the values of a candidate. If you get an invitation for another interview within a couple weeks, you passed this interview. The second interview will be about the position they find you'd be a good fit for.
As for my experiences, because I was previously a temp there and my performance was well received, I had it easy. Having that kind of reputation during a temp assignment will significantly give you an advantage in becoming a permanent employee.
For the most part, I'd suggest preparing for the standard interview questions. Like I mentioned in the beginning, this is a preliminary screening based on a candidate's values and how they fit with the company. Being a phone interview, it should be a cakewalk if you prepare your notes right.