Mobile Broadband Disconencted (AT&T)

I purchased the unlocke version through Amazon. Took it to AT&T and got a SIM card and had it activated. It will not connect to ATT network. Was on support with AT&T and inputted APN settings as follows:

Name: ATT Mobile 7

APN: Broadband

Authentication: none

PDP: IPV4V6

PDP Roaming: IPV4

AT&T advised since it is not an AT&T specific device (unlocked) they cannot help any further.

Anyone have any suggestins?