A normal seat reservation is NOK 50 in 2nd class and free of charge in 1st class (“Pluss”) when booked via Entur.
I'm not sure if you can book a rest compartment with Interrail. The best is to ask Vy or Entur (add +47 for Norway); you can also book via Entur and have the reservations sent via email.
I don’t know what a rest compartment is or do you mean a sleeper on the overnight train? As above Entur can book it all with a short phone call. This is the only way to book these trains.
I don’t know what a rest compartment is or do you mean a sleeper on the overnight train? As above Entur can book it all with a short phone call. This is the only way to book these trains.
Deutsche Bahn and SNCF can also book Norwegian trains, but then 1st class is not free of charge.
When you look up day trains for Oslo - Bergen on entur.no, then you'll see you can book a rest compartment. It looks like a couchette compartment that you can book for use of up to 6 people.
I don’t know what a rest compartment is or do you mean a sleeper on the overnight train? As above Entur can book it all with a short phone call. This is the only way to book these trains.
Nono Vy and some others started to operate “Rest Compartments” with seats similar to the Railjets Business Class or the Hungarian 1st Class plus. They are even similar to some Businessclass seats on Planes.