[JrRifleCoach]

Just opened the box on a used flip that claimed to be unlocked.

After installing my AT&T SIM the face shows an invalid sim and only T-mobile service.

After searching this forum I'm without an answer.

Thanks

[Dubdub]

Didn't search very hard. From the FAQ: How do I determine if my BlackBerry is "unlocked"? - BlackBerryFAQ

[JrRifleCoach]

Duh! I didn't search for my topic.

Many thanks for your keen guidance