Voip Api I Need A Free VOIP Calling Api On My Website Which Allows To Call Only Usa?

I need a free VOIP calling api on my website which allows to call only usa? - voip api

Most of you have known in May VOIP I've seen some websites that you can call to landline or the United States free of the browser
Is there a website that has me on my website in the API as a community, so please let me know to put the resources or processes