Who owns an iPhone knows about the rigor of authorized service. Until recently you were denied service if your screen was replaced in an unauthorized service or was not a screen by Apple. The same with the battery. But Apple changed this policy without making an announcement.
So if you have an iPhone and you've changed your battery or screen to another service, you can get your phone to warranty at Apple. If I did not understand, if you had a problem with the loudspeaker before, and you changed your screen or battery with some non-original ones, the phone was refused to service even if the problem was not on the two components.
Apple made no official announcement but just confirmed the MacRumors rumors, and the change is being applied worldwide. Not even the employees of Apple's authorized centers have been announced for change.