Unlocking N80

I've got a N80 locked on Orange, which isn't a problem as such except I'm shortly moving to Dubai, so my questions are:-

a) Do I need to unlock my N80 to use it with an Etisalat simcard? (Etisalat are the sole mobile phone service provider in UAE)

b) If I do need to unlock the N80, is it possible and if so, can someone point me in the right direction.

Thanks