Is it possible to switch a telus iphone 3 to a bell plan?

i chopped up my black berry with the lawnmower a while ago (dont ask me how) and my friend is selling me his old iphone 3, im with bell and it would cost like 600 bucks to get out of the stupid contract im stuck in, his phone was a telus phone, im wondering is i can switch it over to bell, my other friend says he can "unlock" it but im wondering if the bell simcard would fit in a telus phone?? if not is there an adapter i can buy for it?
Any help is appreciated
Thankyou