You can create a URL to FaceTime to initiate a call. See https://developer.apple.com/library/archive/featuredarticles/iPhoneURLScheme_Reference/FacetimeLinks/FacetimeLinks.html#//apple_ref/doc/uid/TP40007899-CH2-SW1
Like this:
let facetimeURL = URL(string: "facetime://my-email@me.com")!
UIApplication.shared.open(facetimeURL)
Topic:
App & System Services
SubTopic:
Core OS
Tags: