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[[Category:Symbian C++]][[Category:How To]][[Category:Code Examples]][[Category:Telephony]]
This article intends to explain how to handle most of the events on a call using CTelephony in 3rd Edition
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<br>
Events handled here are:
# Call Ringing
# Call Answered
# Call connecting
# Call connected
# Call disconnected
# Dial call

<br>
The implementation is so simple. The idea is simply active object listening to change in voice line
<br>

== Headers Required ==
<code cpp>
#include <Etel3rdParty.h>
</code>

== Libraries Required ==
<code cpp>
LIBRARY   etel3rdparty.lib
</code>

== Capability Required ==
<code cpp>
 Capability  NetworkServices
</code>

== Code ==
The following code assumes that you have a class for log text (CMyLog).

Define observer interface to be implemented by class you want it to be notified with events (if you like) 


== MPhoneReceiverObserver ==

<code cpp>
#ifndef MPHONERECEIVEROBSERVER_H
#define MPHONERECEIVEROBSERVER_H

class MPhoneReceiverObserver
{
public:
	virtual void CallRinging() {}

	virtual void CallAnswered() {}

	virtual void DialingCall() {}

	virtual void CallConnecting() {}

	virtual void CallConnected() {}

	virtual void CallDisConnected() {}

};

#endif // MPHONERECEIVEROBSERVER_H
</code>


Define the active object that will listen to any change in voice line status


== CPhoneReceiver Declaration ==


<code cpp>
#include <e32base.h>	// For CActive, link against: euser.lib
#include "Etel3rdParty.h"	//For CTelephony, link against etel3rdparty.lib

#include "MPhoneReceiverObserver.h"
#include "MyLog.h"

class CPhoneReceiver : public CActive
{
public:
	// C++ constructor
	CPhoneReceiver(MPhoneReceiverObserver& aPhoneReceiverObserver);

	// Second-phase constructor
	void ConstructL();

	// Cancel and destroy
	~CPhoneReceiver();

public: // New functions
	// Function for making the initial request
	void StartL();

private: // From CActive
	// Handle completion
	void RunL();

	// How to cancel me
	void DoCancel();

private:
	//Define object to CTelephone to manage calls
	CTelephony*				iTelephony;

	CTelephony::TCallInfoV1 		iCurrentCallInfo;
	CTelephony::TCallInfoV1Pckg		iCurrentStatusPckg;

	CTelephony::TCallId			iCallID;

	MPhoneReceiverObserver&			iPhoneReceiverObserver;


};

#endif
</code>


== CPhoneReceiver Implementation ==

<code cpp>
#include "PhoneReceiver.h"

CPhoneReceiver::CPhoneReceiver(MPhoneReceiverObserver& aPhoneReceiverObserver) 
	:	CActive(EPriorityStandard),
		iCurrentStatusPckg(iCurrentCallInfo),
		iPhoneReceiverObserver(aPhoneReceiverObserver)
{
}

void CPhoneReceiver::ConstructL()
{
	//Create new object to telephony
	iTelephony = CTelephony::NewL();
	CActiveScheduler::Add(this);		// Add to scheduler
}

CPhoneReceiver::~CPhoneReceiver()
{
	Cancel(); // Cancel any request, if outstanding

	delete iTelephony;
}

void CPhoneReceiver::DoCancel()
{
	iTelephony->CancelAsync( CTelephony::EVoiceLineStatusChangeCancel );
}

void CPhoneReceiver::StartL()
{
	Cancel();		// Cancel any request, just to be sure

	//Notify of change in telephone line
	iTelephony->NotifyChange( iStatus, CTelephony::EVoiceLineStatusChange, 
		iCurrentStatusPckg );

	SetActive();			// Tell scheduler a request is active
}

void CPhoneReceiver::RunL() 
{
	if(iStatus.Int() == KErrNone)
	{
		//Get call status
		CTelephony::TCallStatus callStatus = iCurrentStatusPckg().iStatus;

		switch(callStatus)
		{
		case CTelephony::EStatusRinging:
			iPhoneReceiverObserver.CallRinging();
			break;

		case CTelephony::EStatusAnswering:
			iPhoneReceiverObserver.CallAnswered();
			break;

		case CTelephony::EStatusDialling:
			iPhoneReceiverObserver.DialingCall();
			break;

		case CTelephony::EStatusConnecting:
			iPhoneReceiverObserver.CallConnecting();
			break;

		case CTelephony::EStatusConnected:
			iPhoneReceiverObserver.CallConnected();
			break;

		case CTelephony::EStatusDisconnecting:
			iPhoneReceiverObserver.CallDisConnected();
			break;

		default:
#ifdef __USE_PHONE_RECEIVER_LOG__
			TBuf<50> num;
			num.Copy(_L("Default: "));
			num.AppendNum(callStatus);
			CMyLog::OpenAndWriteToFile(num);
#endif
			break;
		}
	}
	else
	{
#ifdef __USE_PHONE_RECEIVER_LOG__
		TBuf<50> num;
		num.AppendNum(iStatus.Int());
		num.Append(_L(" -- "));
		CTelephony::TCallStatus callStatus = iCurrentStatusPckg().iStatus;
		num.AppendNum(callStatus);
		CMyLog::OpenAndWriteToFile(num);
#endif
	}
  
        //Notify every time before activate object
	iTelephony->NotifyChange( iStatus, CTelephony::EVoiceLineStatusChange, 
		iCurrentStatusPckg );

	if(!IsActive())
		SetActive();

}

</code>
== Output ==
The following is a sample for the log file written above<br>
<br>
Log:25-4-2009-15-18-53<br>
////////////////////<br>
Call Ringing<br>
////////////////////<br>
Call Answered<br>
////////////////////<br>
Call connected<br>
////////////////////<br>
Call disconnected<br>
////////////////////<br>
Default: 1                             //Line Idle<br>
////////////////////<br>