Sets the duration, in milliseconds, of the T398 signaling timer on this port, defaulting to 4000 ms; this is an ITU-T Q.2931 timer related to leaf-initiated join procedures, governing a shorter-interval retry within that same signaling exchange, per ITU-T Q.2931. Admins normally leave signaling timers at their standard defaults, adjusting them only to interoperate with a far-end switch that uses nonstandard timer values or to work around a specific signaling interoperability issue.