NSB operate local trains in the Oslo area as well as regional trains to a number of places around Norway.
NSB is the national Norwegian railway company, and offers excellent train services in Norway and between Oslo and Gothenburg.
Train tickets and information about schedules, prices and services are available at nsb.no, tel. 815 00 888 and at the train stations in Oslo.
Most of NSB's regional trains offer free wireless internet, but you must register on My page on nsb.no in order to use it.
From outside Norway, call (+47) 820 54 388 (NOK 0.59 + NOK 6/min.).
Groups of ten or more can call (+47) 815 00 888 to enquire about discounts.
NOTE: Disruptions in the train traffic this summer (until 7 August)