def update(data)
      headers = @client.make_request(:post, @client.concat_user_path("#{CALL_PATH}/#{id}"), data)[1]
      if headers[:location]
         Client.get_id_from_location_header(headers[:location])
      end
    end
def update(data)
      headers = @client.make_request(:post, @client.concat_user_path("#{CALL_PATH}/#{id}"), data)[1]
      if headers[:location]
         Client.get_id_from_location_header(headers[:location])
      end
    end
Make changes to an active phone call. E.g.: transfer, hang up, answer or reject incoming calls, call recording, etc.
 @param data [Hash] changed data
 @example
   call.update(:state=>"completed") #hangup a call