Let's look at both what the Norwegian government and a webiste for students says. In 2011, the government said you should be able to live for NOK 9080/month. The webiste I link to below says it's closer to NOK 12000/month.
Housing oustide of Oslo should run about NOK 2500-NOK 4000
In Oslo it's more like NOK 3000-NOK 6000 with some fancier options.
If you're an international student, you're prioritised for housing.
https://www.sio.no/bolig/boligoversikt
Food, on the other hand, is much cheaper in Oslo. Elsewhere, you have pretty much the same stores selling thig
ngs for the same prices. You'd probably spend around NOK 2500-NOK 3000. In Oslo, you shouldn't spend more than NOK 2000/month and eat *well*. Grønland has several nice, cheap stores that have good quality meat and veggies.
I have to disagre with the article that says telefon/media use is around NOK 1400. I have a fairly big data plan on Telenor (the most expensive phone company), and I pay NOK 349. I pay NOK 399 for my internett. I don't know anyone who even bothers with cable. It's cheap to buy DVDs, and NRK has free internet streaming.
As for the rest. Textbooks can be borrowed from the library or bought second hand. Still, expect to spend between NOK 1000-2000 a semester and be pleasantly surprised if it's less. If you don't come from a cold country, your first set of winter clothes is going to be an investment. Otherwise you can buy clothes at semiannual sales for reasonable prices.
Going out and free time? That's on you to decide. You can easily spend NOK 1000 on a night out without being extravagant. You can also spend a lot less if you like nature, geochaching, skiing (once you have the equipment). You can also spend less by drinking at the student bars on campus, keeping an eye on the student entertainment (which, pretty good most places).
http://www.studenttorget.no/index.php?show=4524&expand=3797,4524&artikkelid=10023