If your administrator has made public IM connectivity (PIC) available on your network, you can communicate with IM users on MSN® and Yahoo!® instant messaging programs.
There are some limitations as to how you can use Communicator Mobile with users of public IM service providers:
You can only send IM messages and view presence information. Voice conversations are not supported.
You cannot have multiparty conversations with PIC users.
You can view the presence status of only those public IM users who are in your Contacts list.
Note: If you have trouble connecting with users of MSN or Yahoo!, contact your system administrator to verify that your network is configured for public IM connectivity.