I only had one of these with a Big Company. This may apply to your particular case, or not at all.
The very first phone screening was with the recruiter. We had a little talk about my background, education, and past experience; then a quick series of trivia-like questions (relevant to the position, though). The recruiter, who wasn't an engineer, was clearly expecting a pre-selected response she probably had next to the question.
I then had a couple of phone interviews, this time with engineers, that were more similar to technical conversations, including some algorithmic and programming questions first, and then some actual coding in Google Docs.
Depending on the company, and the volume of resumes they get, they may skip the initial HR screening and get you interviewed directly by an engineer.