Actually, Comair lets you keep your number for 5 years. You can do what you want until recall.

On the other hand, new-hires at Comair (and many other places) must drop their number if coming from another airline; Comair doesn't want to train them just to have them get recalled at their old airline six months later.

If you've heard furloughed Comair guys talk about losing their number, it's because Mesaba requires them to resign entirely from Comair before starting training at XJ.

Good luck to you guys.