From Forum Nokia Wiki

CImsiReader example illustrates how to read IMSI (SIM card's identity number, which has nearly nothing to do with the MSISDN that is the phone number used for calling) in 3rd Edition Symbian devices. Note that this code will most likely not work in the emulator, thus you should only use it in real devices.

IMSI_Getter.cpp

#include <COEMAIN.H>
#include <BAUTILS.H>
#include <apmrec.h> 
#include <apgcli.h>
#include <smut.h> 
 
 
CImsiReader* CImsiReader::NewL(MImsiObserver* aObserver)
    {
    CImsiReader* self = NewLC(aObserver);
    CleanupStack::Pop(self);
    return self;
    }
 
  
CImsiReader* CImsiReader::NewLC(MImsiObserver* aObserver)
    {
    CImsiReader* self = new (ELeave) CImsiReader(aObserver);
    CleanupStack::PushL(self);
    self->ConstructL();
    return self;
    }
    
  
CImsiReader::CImsiReader(MImsiObserver* aObserver)
:CActive(0),iObserver(aObserver),iImsiV1Pkg(iImsiV1)
{
}
 
CImsiReader::~CImsiReader()
{
	Cancel();
	delete iTelephony;
	
}
 
void CImsiReader::ConstructL(void)
{	
	CActiveScheduler::Add(this);
 
	iTelephony = CTelephony::NewL();
	iTelephony->GetPhoneId(iStatus,iIdV1Pkg);
	SetActive();
}
 
void CImsiReader::DoCancel()
{
	iTelephony->CancelAsync(CTelephony::EGetSubscriberIdCancel);
}
 
 
void CImsiReader::RunL()
{
	iTelephony->GotIMSIL(iImsiV1.iSubscriberId,iStatus.Int())
}

IMSI_Getter.h

#include <e32base.h>
#include <F32FILE.H>
#include <d32dbms.h>
#include <BADESCA.H>
#include <Etel3rdParty.h>
#include <MTCLREG.H>
 
 
	class MImsiObserver
	{
	public:	//	New methods
		virtual void GotIMSIL(const TDesC& aIMSI, TInt aError) = 0;
	};
 
	class CImsiReader : public CActive
	    {
	    
	public:
		static CImsiReader* NewL(MImsiObserver* aObserver);
		static CImsiReader* NewLC(MImsiObserver* aObserver);
		~CImsiReader();
	protected:	
		void DoCancel();
		void RunL();
	private:
		CImsiReader(MImsiObserver* aObserver);
	    void ConstructL(void);
	private:
		MImsiObserver* 					iObserver;
		CTelephony* 					iTelephony;
		CTelephony::TSubscriberIdV1 	iImsiV1;    
    	CTelephony::TSubscriberIdV1Pckg iImsiV1Pkg;
	    };

See Also

• IMSI on Wikipedia
• Online tool to analyze IMSI
• DevInfo - Get the IMEI, IMSI, CellId etc., synchronously on 3.x devices.