VC++ mfc convert  from 'LPTSTR' to 'const char *'

I passed values for below function:-
 
HANDLE PortSIP_initialize(SIPCallbackEvent * callbackEvent,
                                      int maxLines,
                                      const char * userName,
                                      const char * authName,
                                      const char * password,
                                      const char * agent,
                                      const char * localIP,
                                      int localSIPPort,
                                      const char * userDomain,
                                      const char * proxyServer,
                                      int proxyServerPort,
                                      const char * outboundServer,
                                      int outboundServerPort,
                                      const char * STUNServer,
                                      int STUNServerPort);
Below is the passed values:-

m_siplib = PortSIP_initialize(m_sipevent, 8, (LPTSTR)(LPCTSTR)m_username,
            (LPTSTR)(LPCTSTR)m_username,
            (LPTSTR)(LPCTSTR)m_password,
            "PortSIP VoIP SDK 4.0",
            localIP, SIPPort,
            /*(LPTSTR)(LPCTSTR)m_UserDomain*/"",
            (LPTSTR)(LPCTSTR)m_sipserver,
            /*m_serverport*/"",
            /*(LPTSTR)(LPCTSTR)m_OutboundServer*/"",
            /*m_OutboundServerPort*/"",
            /*(LPTSTR)(LPCTSTR)m_StunServer*/"",/*m_STUNSERVERPORT*/            
            m_stunserverport);

When I compiled then give below Error message in code.

error C2664: 'PortSIP_initialize' : cannot convert parameter 3 from 'LPTSTR' to 'const char *' and  when I double clicked the error the error code pointer point to the last parameter.
When I  hard code the parameter 3 with "  "janith"  "  then give error message,

'PortSIP_initialize' : cannot convert parameter 4 from 'LPTSTR' to 'const char *'

Then also  error pointer  point to  last variable.

I use "Visual Studio 2005"  with Operating system "Windows XP" and use "MFC" with Vsual C++.  

How can I find the cause ? and fix it ?
Start Free Trial

1:
2:
3:
4:
5:
6:
7:
8:
9:
10:
11:

sample Output
 
1>------ Build started: Project: dialler_sample_1, Configuration: Debug Win32 ------
1>Compiling...
1>dialler_sample_1Dlg.cpp
1>e:\sip\sip_2\dialler_sample_1\dialler_sample_1\dialler_sample_1dlg.cpp(227) : warning C4244: 'argument' : conversion from 'time_t' to 'unsigned int', possible loss of data
1>e:\sip\sip_2\dialler_sample_1\dialler_sample_1\dialler_sample_1dlg.cpp(384) : error C2664: 'PortSIP_initialize' : cannot convert parameter 4 from 'LPTSTR' to 'const char *'
1>        Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast
1>Build log was saved at "file://e:\sip\sip_2\dialler_sample_1\dialler_sample_1\Debug\BuildLog.htm"
1>dialler_sample_1 - 1 error(s), 1 warning(s)
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========