firewall setup for different locations

[Howard Mintzer]

I use zoneAlarm as a firewall. When I use my laptop at any of my offices 
I have different ip addresses (the router's external address) which I've 
configured zonealarm to put in their trusted zone. My worry is that when 
I'm away, say using my laptop in a hotel with wifi. How can I access my 
work or home computer then since i won't know the ip of thier router in 
advance and zonealarm will automatically reject it?

Thanks
Howie