I have recently installed a point to point T1. An Adtran TSU 120 is being used to break out channels to connect to an Avaya PBX and channels to connect to a Cisco 1741 router (this is the configuration on both sides of the T1). The routers are using WIC-1T serial interfaces and connected to the v.35 interface on the CSU.
Voice traffic is passing without a problem on the line, however I am unable to get the line protocol on the cisco router up. The carrier has told me that I have to provide clocking on the line, so I have set one TSU120 for internal clocking and the other for network clocking. This does not seem to solve the problem. I have tried both HDLC and PPP encapsulation. Those do not work either. I have to believe I have a configuration problem but am not sure where.