unlock code required for samsung 400i mobile phone?

Answer 1

Sometimes. Take it back to the dealer you bought it from. You may have just pushed the wrong button.
When I first got my new Samsung, I was going through setting it up for my individual preferences and came to a password page. I decided not to put in any lock/unlock code for convenience reasons. The only reason I would need a lock code is if it got stolen, and I use it so much that I would miss it before the thief had the chance to do much damage before I stop service. Good luck.