I tillegg spiller Fossum i bl.a, Funky Butt, The Sinatra Songbook, Kaba Orchestra, Prima Vista Social Club, Jens Fossum "Bass Detetector" , Rubber Soul Quartet, Cannonballs ( med bl.a Eckhard Baur), The New Swing Generation, Inge Stangvik Kvintett, John Surmans Rainbow Studio-Band, Lars Erik Gudims Orkester, Jens Wendelboes "Crazy Energy Orchestra", Norske Store Orkester For Jazz, Sharp 9 ( Staffan William-Olsson ), Børre Dalhaugs BigBandBlast, Bunch of Chops.