Just put a trial sell order to see (much above the current PPS, so that it wont execute) - If they have shares to short - They will show you - Else, they will say "not enough shares available right now".
For a ticker as heavily traded as NOK, it should be easy - Almost every broker will have shares IMO.
Be careful while shorting though - You must exercise caution.
With a stock like NOK - You need to play with more $$$ to make any worthwhile gains coz it moves less.
You can short more volatile stocks for better % wins.