we have a 3660 with NM4T (V.35) at one end and 7206 with PA-MC-8TE1+(G.703) at another end. It is connected through 2MB Lease line with /30 Ip. Interface and line protocol is up on both the side.From 3660 we are able to telnet 7200 router, but from 7200 we are not able to telnet 3600. the moment we telnet 3660 from 7200, line protocol goes down and come up and we loose connectivity i.e the screen hangs. We enabled ospf. The adjacency is formed, still one way telnet is not happening. No access-list is configured. After replacing 1841 router with WIC1T(V.35) card on both side, we were able to telnet from both direction. So we cannot say there is problem with the link. has anyone faced similar problem. If yes, please let me know what is the solution.