anchor.diff:      1800 = nksip_dialog:meta(invite_session_expires, Dialog1A),
       undefined = nksip_dialog:meta(invite_refresh, Dialog1A),
       1800 = nksip_dialog:meta(invite_session_expires, Dialog1B),
  -    true = is_integer(nksip_dialog:meta(invite_refresh), Dialog1B),
  +    true = erlang:is_integer(nksip_dialog:meta(invite_refresh), Dialog1B),
   
   
       % Lower time to wait for timeout
  
positive.code:     1800 = nksip_dialog:meta(invite_session_expires, Dialog3A),
      undefined = nksip_dialog:meta(invite_refresh, Dialog3A),
      1800 = nksip_dialog:meta(invite_session_expires, Dialog3B),
      true = is_integer(nksip_dialog:meta(invite_refresh), Dialog3B),
      1800 = nksip_dialog:meta(invite_session_expires, Dialog3A),
      1800 = nksip_dialog:meta(invite_session_expires, Dialog3A),
      {ok, 200, []} = nksip_uac:bye(Dialog3A, []),
  
negative.code:     timer:sleep(100),
      Dialog4B = nksip_dialog:remote_id(Dialog4A, ua3),
      1800 = nksip_dialog:meta(invite_session_expires, Dialog4A),
      true = erlang:is_integer(nksip_dialog:meta(invite_refresh), Dialog4A),
      undefined = nksip_dialog:meta(invite_session_expires, Dialog4B),
      undefined  = nksip_dialog:meta(invite_refresh, Dialog4B),
      1800 = nksip_dialog:meta(invite_session_expires, Dialog4A),
  