The routing of a call or message over a substitute route when a primary route is unavailable for immediate use. 2. In signaling, the process of allocating substitute routes for a given signaling traffic stream in case of failure(s) affecting the signaling links or routes involved in the normal routing of that signaling traffic stream. [T1.226-1992] [..]

A mechanism that supports the use of a new path after an attempt to set up a connection along a previously selected path fails. Alternating Current Generator

The routing of a call or message over a substitute route when a primary route is unavailable for immediate use.