Question : Need to know port Exchange Free Busy sync runs over

We are exchanging free busy info with another company we acquired. They have a separate Exchange Org. We are using the Microsoft Exchange Free Busy sync tool Everything was set up and working for the longest time. Then it just stopped. I get errors and the log has a very generic error of "unable to initialize mapi interface" Email flows OK and I can telnet to port 25 on the Exchange server. Its just the Free Busy that does not work. Does this product have a specific port it runs over?

Answer : Need to know port Exchange Free Busy sync runs over

To be sure run from a command box the netstat -a -b 10
The -a shows all connections to and from the server and the port numbers
-b shows the exe so you can be sure it is the right one
the 20 is a time in seconds for the command to re-run if need be.