ISDN Dialer load Threshold

Just have a questions about the "dialer load-threshold load [outbound|inbound|either]" command.

I have currently set up my router to use "dialer load-threshold 25 either" to bring my second ISDN line up when traffic in either direction reaches 10%. I was wandering if there was a command to have the second line up permanently?

Any assistance would be much appreciated.