According to various travel planners, including Entur, Opentripplanner and Transitfeeds, there is a 03:28 bus from Namsskogan stasjon to Smalåsen, presumably timed to correspond with the arrival of the train from Trondheim. I can find very little other information on this bus, other than that it is a bestillingsrute, driving only on request. It is apparently operated by Indre Namdal Trafikk A/S who appear to have no internet presence. I found a 2012/2013 timetable (6 years old) that does not mention this bus line to Smalåsen, but it does explain that Bestillingstransport består av tilbringertransport og servicetransport. and Tilbringertransport gjelder alle som bor eller oppholder seg i nevnte kommuner og har lengre avstand til buss og togstopp enn 2 km. and Servicetransport er for deg som trenger transport til butikk, bank, postkontor eller andre service kontorer. Transporten kjøres på faste dager til faste tider. which appears to mean it's a pre-order bus (no surprise there) and/or only for residents or for transport to shop, bank, post office, etc (and then only twice a week). Neither of those apply to me and according to the aforementioned sources the 17-599 appears to run every weekday. Can I, as a tourist, pre-order transport on this bus 17-599 to travel to Smalåsen (gateway to Børgefjell National Park, in case anyone wonders why) in connection with an arriving train?
I just asked the customer service and there is a bus service operating on demand between Namsskogan station and Smalåsen for every train stopping in Namsskogan.
The service must be ordered in advance, either by contacting customer service by phone +4707417 or +4775771861 (the short service number is not necessarily reachable from outside Norway).
The price for an adult ticket is 60 NOK if paid cash, or 37 NOK if paid with T:kort (an electronic prepaid travel card) or with the Mobilett app.