A patent granted to Apple on Tuesday could be enabled into a feature that tells you if someone is available for a FaceTime or cellular call before you even attempt to contact them. Apple Insider made note of of the new patent grant, saying it could provide "IM-style system status information that can be viewed dynamically by other users."
Unlike a basic presence indicator like you'd see in a traditional IM app, Apple's implementation would be a little more advanced based on the patent details. There's no guarantee of course that Apple will actually implement it, but it's a clever approach, and one I'd like to see come to fruition.
Central servers, for example, would continuously monitor various settings on an iPhone such as if the ringer or vibration motor is on, signaling a call recipient's intent to receive incoming calls or not. Battery life, location and cellular signal strength could also be parameters to determine if now is the right time for a call to be placed.
Of course, this means users would actually allow Apple to receive such data for this service. Apple Insider says it would be up to iOS device owners to enable or disable the feature, much like how the Find My Friends app works: In that case, iPhone owners actually have to accept a request to share their location with specific contacts.
While some people won't want to use this type of presence indicator -- that's assuming Apple even implements it -- I'm one of those that would. There are times when I don't want any incoming FaceTime or cellular calls that are outside of my normal do not disturb settings, for example. That's even more important to me now that Apple's iPads and computers running OS X Yosemite can accept those same calls over Wi-Fi; sometimes, I just don't want a call or FaceTime conversation to interrupt my work.