Thanks for posting! Generally speaking, we do not recommend the Total Access 900 series units be used in a bridging (extend your LAN) application. There are a few reasons for this, but the most important is that you cannot inplement QoS on bridged interfaces. If the unit will be running VoIP, this will be an issue. In a routed environment, the TA 904 should work fine. Typically you will have similar units on each end of the T-1 that will run a protocol such as PPP. Configuring PPP in AOS is the guide you will want to reference for setting this up. Below is a very basic example which is shown on page 38 of the linked guide.
interface eth 0/1
ip address 184.108.40.206 255.255.255.248
interface t1 1/1
tdm-group 1 timeslots 1-24 speed 64
interface ppp 1
ip address 220.127.116.11 255.255.255.252
cross-connect 1 t1 1/1 1 ppp 1
ip route 0.0.0.0 0.0.0.0 ppp 1
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