This article assumes that you are currently running Trillian as an IM client.
Right-click on Trillian. Under Manage Connections, choose Add a new Connection. ChooseJabber/XMPP.
Next it will prompt you for your JID and your password. Your Jabber ID (JID) is your SIP address, firstname.lastname@example.org and your password is your WWW password.
Choose the Settings button. Set the Server Hostname to "xmpp-client.onsip.com" and keep port 5222.
Note: It is not recommended that you run Trillian and My.OnSIP.com via Prism at the same time.