I just found this question and thought it needs a more comprehensive answer: As of PHP 5.4 there are three methods to accomplish this: Assembling the response code on your own (PHP >= 4.0) The header() function has a special use-case that detects a HTTP response line and lets you replace that with a custom … Read more
A clear explanation from Daniel Irvine [original link]: There’s a problem with 401 Unauthorized, the HTTP status code for authentication errors. And that’s just it: it’s for authentication, not authorization. Receiving a 401 response is the server telling you, “you aren’t authenticated–either not authenticated at all or authenticated incorrectly–but please reauthenticate and try again.” To … Read more