As you probably know Office Communication Server 2007 from Microsoft supports and can very easily be seutp for federation with the public IM providers. Yahoo, MSN and AOL are the supported protocols. Microsoft kindly provides the intial setup and it works. For MSN connectivity, you can add any "Live Enabled" email address to your contact list and IM it just as though it was inside your organization. Adding an @AOL.com address or an @yahoo.com address simply allows the same connection.
The catch/configuration comes on the client side, when you as an OCS user want to contact a MSN user that has configured their personal or work email as their "Live enabled" MSN IM id, you must change the way you represent their email address. If the MSN IM email Live Enabled email address is aaron@example.com, you would format it as aaron(example.com)@msn.com.
We lately have had some issues with one provider in particluar though. MSN federation has been giving us fits. We continue to get reports from our users that they have intermittent problems, that MSN users report intermittent problems sending IMs to them and that in general the level of frustration is running high.
We have contacted PSS, and through them contact has been made with the MSN team and so far, we have no resolution. Working with MSN we came to suspect our Firewall, we came to suspect our ISP and we came to suspect our hardware. We undertook testing and ruled out the firewall, we can’t find a place to lay blame on any of our service providers or our hardware. At this point, we still don’t know the cause and don’t have an end resolution. Sorry to say it, dear reader, but that is the fact as it sits. We have errors, that lots of other OCS systems have, about errors federation with the MSN server, X many in the past day and so on. Nothing can be done. The product is great and I have to thank Derek Seaman for working with Microsoft PSS on this issue.