OCS has the capability to make and receive phone calls if a number has been setup for you. Are there plans to implement this functionality?
CSTA functionality, i.e. PBX control, is already implemented.
Please clarify what you mean by "OCS Phones".
If it's regular desktop phone, then SIPE can make a call with it's use. Right-click on contact for context menu, then click on it's phone number. Desktop phone (of course if your office PBX is integrated with Communications Server) will start a call.
If you mean VoIP (Voice over IP, soft phone feature) then currently there is not such functionality.