If you don't know - ocs talks SIP over TCP. Why is this a big deal ? Most open source implementations like SIP over UDP for performance reasons amongst others. While I've fielded a lot of flack on the SIP over TCP implementation, the OCS team have an awesome blog entry on why they made the choices they did. Have a read here:
Kudos again to the dudes for a great blog entry - sure helped me explain their design decisions.