The issue doesn't appear to be fixed in the latest iOS 11.2.5 software update, and based on the complaints, it would appear that all versions back to at least iOS 11.2 are affected. Earlier versions of iOS 11 could be affected too.
MacRumors hasn't been able to reproduce this issue, and we've seen
only a handful of comments on our discussion forums related to the matter, but we did find a dozen more complaints from users across
Twitter and
Reddit.
Article Link:
Apple is 'Looking Into' Limited Reports of Incoming Call Delays on iPhone X