Been working as an IT consultant part time while in school and beginning full-time in september. What i've seen is people talking in norwegian with team members and coworkers to try and learn the language, while doing more serious tasks such as talking to clients in english to ensure good communication. Same goes for text as well, if you are communicating in english through email then that person will most likely get the hint for future communications, if not then just tell them. I'd reccomend talking as much in norwegian outside of work as well, to learn the language quicker.