The talk about Siri’s iPhone 4S exclusivity being nothing more that marketing started right after the announcement of Apple’s new flagship smartphone. And while this is a very “convenient” explanation for various random tech blogs, in reality important products decisions are rarely made with such simple reasoning, especially at Apple or any other company, that is focused on quality of their products and the user-experience that they create.
So what are the real reasons for including Siri only in the iPhone 4S? Only people at Apple know that, but we can try to guess. So, here’s a list of possible reasons, that could have affected Apple’s decision:
- — CPU Performance. While the iOS ecosystem doesn’t really suffer from fragmentation, devices in it do differ from a performance standpoint. And while the A4 in the iPhone 4 (and other devices, like the 4th generation iPod Touch and the original iPad) may be able to handle Siri (as claimed by the jailbreak screen hackers), it’s a whole different question if it can be done reliably and good enough by Apple’s standards. Will Siri feel responsible enough, when the A4 is under load from third-party apps? Probably not.
- — Memory availability. The amount of RAM in iOS 5 compatible devices ranges from 256 to 512 megabytes, with only three of all iOS 5 compatible devices having 512 Mb of RAM: iPhone 4, iPhone 4S and the iPad 2. And while I didn’t work on Siri, I imagine it can be one hell of a RAM hog, especially considering that it needs to be a system-wide service and stay usable even when running third-party apps in the background.
- — Internet availability. It’s not a secret that Siri is heavily reliant on the device having an internet connection, with most of the voice-processing happening in the cloud, web services (like Yelp and WolframAlpha) are also heavily utilized by Siri. Considering this, it would be nearly pointless to enable Siri on devices that don’t have an always available data connection. And what iOS devices have an always available data connection? Only iPhones (while technically iPads with 3G have a data connection, it couldn’t be considered always available since the plans encourage users to manually activate it only when needed).
- — Relevance. Siri is a personal assistant, whose main purpose (aside from the “open the pod bay doors” jokes) is to help you do stuff either more convenient, or do it in situations, when you can’t (or shouldn’t) do it manually, e.g. when driving. You don’t need to be a rocket scientist to figure out, that most of these use cases are relevant for a phone, i.e. a personal mobile device, which is always with you. Sure, there could potentially be uses for Siri on an iPod Touch, but they are significantly limited, compared to the iPhone, since iPods are mostly mobile entertainment devices. And the iPad is just too big for the most of Siri’s use cases, many of which include either doing stuff (e.g. replying to a message or scheduling a meeting) on the go, or just simplifying tasks, that aren’t that convenient to do on a small smartphone screen.
- — Smooth rollout. I think it’s obvious that the best way to release any new product (or rather a service), that will be used by a large user-base (especially the one with a web back-end), is to do a smooth rollout. Smooth rollouts can be used either to minimize problems with network capacity (to prevent the servers from getting slammed because of hype), or just to work out unexpected problems that can (and will) arise, when the product is finally launched. This is particularly true for services, that are in beta-stage — it’s a mystery to me why people in the gadget sphere don’t notice the “beta” sign on Siri’s page. It’s beta for a reason. And while there are different ways to do a smooth rollout for something like a web-only service (e.g. Google used invites when launching Gmail, Wave and Google+, etc), Apple’s options for Siri were limited.
As some of you may have noticed, this list of reasons was composed in order of increasing probability. That being said, I don’t think that Apple’s decision was affected only by one of these reasons — more likely, it’s some combinations of them. Apple’s reasons will become more clear when new devices (like the iPad 3 and the next generation iPod Touch) start appearing. Right now I can’t completely rull-out the probability of Siri becoming available on older devices sometime in the future.