Hey Sheep,
From my Experience with those type of preliminary phone screenings, it is unlikely it will get into anything technical. Usually they are used as an initial screening to see if you would even remotely be fit for the role. So expect them to ask "tell me about yourself" type of interview questions, and you should also take this time to learn more about the role.
Studying Technical shenanigans is unlikely to make much of a difference, so i would just make sure you have the generic "who are you/ what are you looking for" answers down cold. Being able to articulate how your previous projects will make you a better candidate for the position will also be a big help. Also sound interesting, nobody likes talking to a dead fish on the phone. But once again this is more used as a screening for whether or not to bother interviewing you, and will probably have little weight on their ultimate decision, so don't fret too much.
Just to give you an idea of what you may expect, I just recently started a junior position at a rather large AAA studio, and they just had an initial 30 minute phone interview (exactly like what your explaining), at the end of the call the guy said "alright sweet, we will be sending you information on how to take the coding test shortly" and then the next day they sent me the technical programming test they do. (So make sure that you have a clear line of action at the end of the call, if not then that probably means they wont be contacting you again). After I "Passed" the technical test (Which was trivial questions... see if you can code out of a paper bag), they invited me in for a long, in-house interview (lasted about 5 hours, met with about 7 different people of varying roles, started with a much more intense technical interview where they questioned me about areas I specifically mentioned I was weak in, probably to see how I would approach problems im not comfortable with). Then a few weeks after that they extended an offer.
Note that your experience may be completely different, Just thought I would share my experience since it seems to be similar circumstances.
My specific call was broken up into basically:
15 minutes talking about me/previous experience/projects
10 minutes talking about the position
5 minutes of us complaining about the heat.
But basically, I wouldnt really bother with "cramming" for an interview. Alot of things take time to fully sink in and understand, so its pretty easy to see through people who just quickly read something, and dont fully understand it. Just make sure you get across that you are excellent at figuring things out and not getting stuck.