I am publishing a LCS 2005 Access Proxy, and I read that it only needs to be open port 5061 TCp, inbound and outbound. I tried several configurations, and in an Access rule I put the "Local Host" network and clients inside the LAN (for test purposes) with all the traffic allowed. The thing is, I can do a telnet to port 5061 to federation.messenger.msn.com from an ISA array member, and I cant do the telnet from any other place (DMZ and LAN). I activate the logging, and I can see the rule saying that that the ISA server connects to federation.messenger.msn.com by that access rule. And from the other clients, it doesnt log anything, until I do a telnet to 5061 to an array member, it logs the attempt.