I need to import a json file into our environment in order to whitelist a long list of IPs - how can i do this?

We are implementing a new Phone System into our environment. When performing our Network Assessment test which tests the ports needed, domains and URLs that need to be accessed and IPs as well that need to be whitelisted. All of our tests come back in the green except for one result which shows an downstream MOS score of 0.  one of the items were were told to do is to import and whitelist a large amount of IPs that are needed for access. I am not sure how to import these IPs which are included in a large json file and how to add these to our network and steps to do this.