{

	* If the request cannot be started then an error will be returned immediately as return value. 

	* In succesfull case KErrNone will be returned and the requested action has been started.

	* If the request cannot be started then an error will be returned immediately as return value. 

	* In succesfull case KErrNone will be returned and the requested action has been started.

	* If the request cannot be started then an error will be returned immediately as return value. 

	* In succesfull case KErrNone will be returned and the requested action has been started.

	* If the request cannot be started then an error will be returned immediately as return value. 

	* In succesfull case KErrNone will be returned and the requested action has been started.

	/**

	* Adds a new call to conference call. 

	* When plug-in regards the call as added it will notify observer about it 

	* with call added notification MCCPConferenceCallObserver::ECCPConferenceCallAdded.

	* 

	* @since S60 3.2

	* @param aCall Call to be added to conference.

	* @return None

	* @leave In case of an error system wide error code.

	* @leave KErrAlreadyExists call is already part of conference.

	* @leave KErrNotReady In case conference is not on hold or idle.

	* @pre Conference call state is MCCPConferenceCallObserver::ECCPConferenceHold or 

	* MCCPConferenceCallObserver::ECCPConferenceIdle. 

	* @post Added call is notified calling MCCPConferenceCallObserver::ConferenceCallEventOccurred.

	* @post If conference becomes active regarding its internal plug-in based logic state is 

	* MCCPConferenceCallObserver::ECCPConferenceActive.

	*/

	virtual void AddCallL( MCCPCall* aCall ) = 0;

	/**

	* Removes a call from conference call. Can be called on any state.

	* When plug-in regards the call as removed it will notify observer about it 

	* with call removed notification MCCPConferenceCallObserver::ECCPConferenceCallRemoved.

	* @since S60 3.2

	* @param aCall Call to be removed from conference.

	* @return None

	* @leave In case of an error system wide error code.

	* @leave KErrNotFound call was not part of conference.

	* @leave KErrNotReady In case conference is not connected (MCCPConferenceCallObserver::ECCPConferenceActive) state.

	* @pre Conference call state is MCCPConferenceCallObserver::ECCPConferenceActive or 

	* MCCPConferenceCallObserver::ECCPConferenceIdle. 

	* @post Removed call is notified calling MCCPConferenceCallObserver::ConferenceCallEventOccurred.

	* @post If conference becomes idle regarding its internal plug-in based logic state is 

	* MCCPConferenceCallObserver::ECCPConferenceIdle. 

	*/

	virtual void RemoveCallL( MCCPCall* aCall ) = 0;

	/**

	* Returns number of calls active calls in the conference.

	* @since S60 3.2

	* @param None

	* @return aCallCount Number of calls in conference.

	*/

	virtual TInt CallCount() const = 0;

	* Switch to a private call with given call that is part of conference. When call is regared 

	* as removed from conference it will be notified using 

	* MCCPConferenceCallObserver::ECCPConferenceCallRemoved.

	* @since S60 3.2

	* @param aCall Call to go one-to-one with.

	* @return None

	* @leave KErrNotFound call was not part of conference.

	* @post After successful actions conference call state is MCCPConferenceCallObserver::ECCPConferenceHold 

	* and private call will become active one. 

	*/

	virtual void GoOneToOneL( MCCPCall& aCall ) = 0;

	* Add all current calls in the plug-in to conference. Each succesfully added call will 

	* be separately notified using MCCPConferenceCallObserver::ECCPConferenceCallAdded.

	* If call is not added to conference it is not notified and can be regareded as not 

	* part of conference

	* @since S60 3.2

	* @param None

	* @return None

	* @leave In case of an error system wide error code.

	*/

	virtual void CurrentCallsToConferenceL() = 0;

	* @since S60 3.2

	* @param aCallArray Reference to call array

	*/

	virtual TInt GetCallArray( RPointerArray<MCCPCall>& aCallArray ) = 0;

	};