Thank you for asking this question in the support community. It sounds like you would like to remove the Trendnet router and use the ADTRAN as the Internet router, as well as the DHCP server. There are several ways you can achieve this.
Here is a video on Configuring Internet Access (Many to one NAT) with the Firewall Wizard in AOS. Following this walk-through wizard video, you will be able to setup the ADTRAN unit to use the T1 as the Internet connection. Furthermore, the Configuring T1 and E1 Internet Access in AOS has detailed information on setting up the T1, firewall, and IP addressing in written form.
Here is a post on how to setup DHCP (it also links the DHCP guide): How do you set up a DHCP pool?
Finally, this post has information on setting up a T1 and assigning public IP addresses for Internet access (for reference): Re: Basic T1 Setup with AdTran Router
I hope that makes sense, but please do not hesitate to reply to this post with any additional questions. I will be happy to help in any way I can.
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