How to add New Models to EPM?

I’m currently using Grandstream phones on FreePBX with EPM 13.0.102

I have just bought HT-804 ATAs to use on my system that replace the HT-704 version. Currently I do not have the HT-804 as an option. how does one add new models to EPM?

If you are talking about the Commercial Endpoint Manager, users can’t add models. Here is the list of supported devices: