Allowing my internal XMPP client to connect to the Talk service

The Google Talk service supports XMPP client to server connectivity.  If your organization has a firewall/ACL that restricts the traffic to or from the Internet, you'll need to make certain changes to allow connectivity with Google Talk service.

Specifically, you must allow your client to connect to all IP addresses resolved on DNS name talkx.l.google.com, TCP port 5222.