[VoiceOps] AT&T OfficeDirect SIP to Mobile

Has anyone deployed AT&T OfficeDirect with a IP PBX solution http://www.business.att.com/content/productbrochures/Office-Direct.pdf ? Seem like an interesting solution, but not sure how well it works or what supports this solution. http://www.tango-networks.com/ seems to have an interesting product that integrates with this solution. Has anyone used Tango? Looks like the have Sprint and T-Mobile integration too.