Is it possible to unlock an iPhone without the top button?

The top 'power/lock' button on my iPhone 4 is broken and I'm wondering if it's possible to unlock the phone to other carriers without it? Anyone have any methods/web sights? Or would I have to repair that first?

Added (1). I do not mean to lock the SCREEN I mean that the phone is locked onto Bell Canada and I'm with Telus and I need the phone unlocked before I can use it.

The home button can be used to unlock the iPhone 4 when it's locked, but not for locking it and turning it off.