How to manage browser background page?

Question

JavaScript

There is a web dialer application based on sip.js. It needs to be designed as a browser extension so that it works in the background.

"background": {
        "page": "index.html",
        "persistent": true
    },
"browser_action": {
        "default_icon": "icon.png",
        "default_popup": "popup.html"
    },

The question is how to manage this index.html from the popup?
Via:

chrome.runtime.getBackgroundPage(function(page){
  console.log(page.document);
});

I get a link to the document of the background page. What should I do next if I'm moving in the right direction?