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:     {ok, 200, []} = nksip_uac:update(Dialog1A, [{session_expires, {2,uac}}]),
  
      90 = nksip_dialog:meta(invite_session_expires, Dialog1A),
      true = is_integer(nksip_dialog:meta(invite_refresh), Dialog1A),
      90 = nksip_dialog:meta(invite_session_expires, Dialog1B),
      undefined = nksip_dialog:meta(invite_refresh, Dialog1B),
  
  
negative.code:     2 = nksip_dialog:meta(invite_session_expires, Dialog1A),
      undefined = nksip_dialog:meta(invite_refresh, Dialog1A),
      2 = nksip_dialog:meta(invite_session_expires, Dialog1B),
      true = erlang:is_integer(nksip_dialog:meta(invite_refresh), Dialog1B),
  
      % Now ua1 refreshes, but change roles, becoming refresher. 
      % Using session_expires option overrides automatic behaviour, no Min-SE is sent
  