From Forum Nokia Wiki

ID	KIS000819	Creation date	February 11, 2008
Platform	S60 3rd Edition, FP1	Devices	Nokia N95 8GB
Category	Symbian C++	Subcategory	Telephony

Keywords (APIs, classes, methods, functions):

Note!
This API is not part of the public SDK. It can be found in the SDK API Plug-in.

Overview

When a phone call is dialed using the AIW APIs, it fails with error code -6(KErrArgument).

Description

The following code can be used to dial VoIP, video, or voice calls using the AIW API:

TAiwDialDataV1 data;
  TAiwDialDataV1Pckg dataPckg( data );
  data.SetTelephoneNumber(telNumber);
  // CallType can be Voice, VoIP, or Video 
  TAiwCallType callType(EAiwVoice); 
  data.SetCallType( callType );
  TAiwNameBuffer name(_L("Callee"));
  data.SetName(name);
  data.SetWindowGroup( CCoeEnv::Static()->RootWin().Identifier() );  
  data.SetShowNumber(ETrue);
  data.SetRemoveInvalidChars(EFalse);
  TPtrC8 ptr;
  ptr.Set( dataPckg );
  TAiwVariant variant( ptr );
  TAiwGenericParam param( EGenericParamCallDialDataV1, variant );
  CAiwGenericParamList& paramList = serviceHandler->InParamListL();
  paramList.AppendL( param );
  //Make call
  serviceHandler->ExecuteServiceCmdL( KAiwCmdCall, paramList,
                                 serviceHandler->OutParamListL() );

This works fine in S60 3rd Edition and S60 3rd Edition, FP1 devices, such as the Nokia N95, but ExecuteServiceCmdL fails with error code -6 KErrArgument in the Nokia N95 8GB.

Solution

Use the 3rd Party Telephony API or Phone Client Dial APIs (part of API Plug-in package) instead of AIW (part of API Plug-in package) in the N95 8GB. This issue is expected to be fixed in future releases of the N95 8GB.