Thanks Meter 5
Join Date: Jul 2006
Location: East Hampton, Connecticut, USA
If you haven't already, you might want to factory reset it. This will wipe everything off the device, but that should be a big deal if you received it as loaner. Go to settings - about - reset your phone. The device is SIM locked and can only use an AT&T SIM unless you get en unlock code from AT&T. Not a big issue if you're an AT&T customer, but a pain if you are not. As for using the device without a SIM card, I do this regularly when I switch to my HTC One but still use my 1020 for the camera, etc.
Device: Nokia Lumia 1020 (primary) / HTC One (backup)