XBee PRO S2 questions

Greetings all,

We have a XBee PRO S2 working as a End-Device and we have some questions which we would like to request some help of this community.

We have programmed the XBee with the PAN ID at 0, so it could join to any PAN ID. Is there any way for the XBee to lose the PAN ID by himself (supposing it already join an existing PAN ID and it is working normally)? How much time does it need to lose the PAN ID?

After losing the PAN ID, if we want the XBee to rejoin the same PAN ID, what is the procedure? Do we need to make a “permit join” on the coordinator for the XBee to rejoin again? Is there any alternative, not involving the coordinator or any router?

Can some one explain more clearly what is the join notification feature? Can it work as a rejoin feature for the XBee as it seems to announce himself on the ZigBee Network?

We appreciate any help on this matter, we already read the documentation but they are not specific for what we have in hands.

I think is relevant to say that the XBee works in Extended Sleep Mode with 1 minute of sleep time and 3 seconds of wake time.