This read-write Integer32 (10-25000, matching the milliseconds unit used by the equivalent per-transport object) sets the default window timeout new Frame Relay over IP transports inherit. An admin tunes this baseline timeout to control how long the FRoIP transport waits for window acknowledgements before considering them lost, affecting all newly created transports under this config. For example, transports built over a higher-latency IP path would need this default window timeout raised so acknowledgements aren't mistaken for losses simply due to normal delay.