I recently made a lot purchase of 80 used RIM 7290 Blackberry phones. Most of them either were stamped AT&T or Cingular on the outside and had matching sim cards inside.

Six of them did not have any name stamped on the outside. They have sim cards in them but there is no carrier brand on the cards. Does anyone know how I can tell which company these were previously used with?

I know nothing of these phones and I guess it is possible that they were never even put into service. It is possible they were only intended as replacements for other phones that workers in the company may have lost or damaged as time went by.

If they were never put into any service before can they be considered as 'unlocked'?