Widget not found with Appium but found with UI Automator

I have a project where a server sends commands to a SIM, and these commands are handled by an applet interfaced to the SIM ToolKit.

The aim of my work is to make automated tests with Appium. However Appium does not see the SIM Toolkit widgets ("click OK view", "write a code" etc), but UI Automator sees them.

My quesiton is: how make Appium get SIM Soolkit widgets? Is there a dedicated configuration to set up for this kind of internal APIs?

Thanks in advance :)