{tapi Errors}

 const TAPIERR_CONNECTED = 0;

 const TAPIERR_DROPPED = -1;

 const TAPIERR_NOREQUESTRECIPIENT = -2;

 const TAPIERR_REQUESTQUEUEFULL = -3;

 const TAPIERR_INVALDESTADDRESS = -4;

 const TAPIERR_INVALWINDOWHANDLE = -5;

 const TAPIERR_INVALDEVICECLASS = -6;

 const TAPIERR_INVALDEVICEID = -7;

 const TAPIERR_DEVICECLASSUNAVAIL = -8;

 const TAPIERR_DEVICEIDUNAVAIL = -9;

 const TAPIERR_DEVICEINUSE = -10;

 const TAPIERR_DESTBUSY = -11;

 const TAPIERR_DESTNOANSWER = -12;

 const TAPIERR_DESTUNAVAIL = -13;

 const TAPIERR_UNKNOWNWINHANDLE = -14;

 const TAPIERR_UNKNOWNREQUESTID = -15;

 const TAPIERR_REQUESTFAILED = -16;

 const TAPIERR_REQUESTCANCELLED = -17;

 const TAPIERR_INVALPOINTER = -18;

{tapi size constants}

 const TAPIMAXDESTADDRESSSIZE = 80;

 const TAPIMAXAPPNAMESIZE = 40;

 const TAPIMAXCALLEDPARTYSIZE = 40;

 const TAPIMAXCOMMENTSIZE = 80;

 const TAPIMAXDEVICECLASSSIZE = 40;

 const TAPIMAXDEVICEIDSIZE = 40;

function tapiRequestMakeCallA(DestAddress : PAnsiChar;

  AppName : PAnsiChar;

  CalledParty : PAnsiChar;

  Comment : PAnsiChar) : LongInt;

 stdcall; external 'TAPI32.DLL';

function tapiRequestMakeCallW(DestAddress : PWideChar;

  AppName : PWideChar;

  CalledParty : PWideChar;

  Comment : PWideChar) : LongInt;

 stdcall; external 'TAPI32.DLL';

function tapiRequestMakeCall(DestAddress : PChar;

  AppName : PChar;

  CalledParty : PChar;

  Comment : PChar) : LongInt;

 stdcall; external 'TAPI32.DLL';

procedure TForm1.Button1Click(Sender: TObject);

var

 DestAddress : string;

 CalledParty : string;

 Comment : string;

begin

 DestAddress := '1-555-555-1212';

 CalledParty := 'Frank Borland';

 Comment := 'Calling Frank';

 tapiRequestMakeCall(pChar(DestAddress),

  PChar(Application.Title),

  pChar(CalledParty),

  PChar(Comment));

end;

end.