Not necessarily, I tried this a couple years ago when I got Sirius.
I bought the unit from BestBuy Canada and registered it through my friend's account which is US based. Basically we registered my unit as his second. Although I registered it with Sirius USA, since the unit has a Canadian ID the programming was actually Canadian not US.
Sony 60" GrandWega, Harmon Kardon AVR230 to Paradigm Monitor 7s,Atoms,10" sub. Also, Sony KDL46W3000 to Sony DAVHDX475