To better understand this type of remote interaction, let's assume we have two offices, one based in Mumbai, and the other based in Birmingham. Both offices run Openfire servers. Now, it would be a great idea to connect users from both of the offices with each other seamlessly and securely:
From their own office
When they are in the other office
From anywhere else in the world
This set up isn't very difficult to implement. But you need to make sure the Openfire servers have a DNS-resolvable name. Openfire servers make a DNS lookup to work out the actual IP address and port to be used to connect to the remote server. If you don't have one, you can use one of the free DNS services on the Web such as DynDNS (see http://www.dyndns.com/).