unable to use the org.doubango.ngn.sip.NgnSipSession Class Reference api's (addheader and remove header)

```

What steps will reproduce the problem?
1. I am trying to use NgnSipSession Class remove header and addheader api's to
add the new header or change the value of existing header

2.i have tried to use this along with hang (config) for add header is working
only for request but not for response.

config.addHeader("Contact", "ajith");
This works for request but not for response

3. so i have tried with ngnsipsession class api 's they are not adding the
below given header

mSession.addHeader
Contact :;
this should be there in response
this does not the contact header in my response

3.

What is the expected output? What do you see instead?

Contact :;
this should be there in response

What version of the product are you using? On what operating system?

android 4.0.3

Please provide any additional information below.

```

Original issue reported on code.google.com by `ajithks...@gmail.com` on 24 Jan 2012 at 5:02