Android: Intent Service with online libraries (retrofit or volleyball)

Question

I am developing an application, and one of the requirements of the application is to use the Intent Service for any network api calls. I am using a modification to extract data from api. Data extraction is not required, but a request is made for the user (for example, the user clicks on an item).

So, why is there a need for an Intent Service if I use Retrofit and it retrieves data asynchronously. Even if it is possible, how can I use the modification using the intent service. Thank.