In one embodiment, a router maintains a communication session between a local terminal unit and a remote terminal unit, the local terminal unit interconnected to the router over a local serial data link, and the remote terminal unit interconnected to the router over an Internet Protocol (IP) session via a remote router and a corresponding remote serial data link. The router may then monitor a state of the local serial data link, and communicates this state with the remote router over the IP session, as well as a remote state of the remote serial data link. The router may then correspondingly control the state of the local serial data link to match the remote state of the remote serial data link.