AT&T U-verse

What are people doing for business U-verse connections? AT&T installs a gateway device that doesn't necessarily allow the business to use their own router/firewall. The AT&T gateway is not just a VDSL modem. At least I have not been able to get it to work. The web interface seems to suggest that a pass-through situation can be configured and I have following al the directions but it doesn't appear to work. Has anyone worked with business U-verse and been able to park a cisco router between the private LAN and AT&T gateway? Tim