send DTMF (OS Symbian v7.0)

I have a next problem. There are some code. It works very well on phones with Series 60 1st Edition (Symbian OS v6.1), but on phones with 2nd Edition(Symbian OS v7.0) I can not send DTMF. Maybe somebody has already came across such situation?

//set server
...
RAdvGsmPhone phone;
CleanupClosePushL(phone);
User::LeaveIfError(phone.Open(server, info.iName));
...
RLine line;
CleanupClosePushL(line);
User::LeaveIfError(line.Open(phone, lineInfo.iName));
...
User::LeaveIfError(iCall.Dial(dialnumber));

RCall::TStatus aStatus;
iCall.GetStatus(aStatus);

if (aStatus == RCall::EStatusConnected){
phone.SendDTMFTones( dtfm );
}

Thanks before hand 😊