When backing up to iCloud the iPhone must be 'locked' - what does this mean?

[iMore Question]

My iPhone 4 lets me set an 'auto-lock' time which is when it automatically turns the display off. However people also talk about being 'locked' to a carrier (cell-phone network service provider).
Which 'locked' must it be to have iCloud backups work?

Cheers.

Beanie

 

[kch50428]

The auto-backups happen when the phone is connected to a charger and the screen is locked...

You can manually back up at will via settings... And the screen does not need to be locked for that...