When SLS is enabled, the MGC list displays a fifth element called SLS. This element is always past the Transition Point. After the Link Recovery search concludes for the primary MGC list (entries above the Transition Point), it searches the alternate MGC list (entries below the Transition Point), ending with SLS, the last choice for the Branch Gateway.

When the Link Recovery search settles on the SLS entry in the MGC list, the Branch Gateway registers with SLS (resident on the Branch Gateway) for its call control.

SLS transitions between four possible SLS states: Unregistered, Setup, Registered, and Teardown.