Please use this driver to download and install driver
http://www.att.com/esupport/article.jsp?sid=KB69886#fbid=mYmrrGRXZEd
And use this guide to configure and use
http://www.att.com/esupport/article.jsp?sid=KB87619#fbid=mYmrrGRXZEd
in my case, I use driver relate to AT 890. I have just downloaded driver, now I can use it to access Inernet normally
I post the guide here for someone who do google search and find this topic like me (I found this topic but cannot see answer, so I had had to continue to find, luckily I could found driver but not easily)
Regards
hadatu