Don't know what they say now, but there was a precedent set back in 2001 if they screw with you..
I was hired Feb 05, 2001 with Spirit. After 9-11, I was furloughed for the month (basically) of Oct., and got called back.
As far longevity AND pay, it was like I never left. Feb. 05 of 2002, I got my raise. AND it was based on DOH, unlike SOME place, where it starts (pay raise) one year from the date of your ride (which was two months later).