I’ve used FaceTime with my phone in my pocket many many times for free voice-only calls. Now that I can use my email address in addition to my AT&T number for FaceTime in iOS5, I pretty much don’t need my phone number anymore. I’ve been using iMessage a lot and it’s amazing. I can’t wait for iOS5 to be out for everyone so I can stop using other SMS-replacement apps. What about non-iOS friends? Well, they will just have to get an iDevice, and worst case it will fall back to WhatsApp, and then Google Voice, and lastly, SMS/MMS.
Apple’s built a peer-to-peer calling system that allows you to call multiple devices using just an email address, with no central service or account management to speak of. All the company has to do is roll out updates that enable voice-only calls and support for calls on 3G and 4G networks, and millions of iPhone 4 users will stop using their minutes when they call each other. What’s more, FaceTime is built on open protocols like XMPP and SIP, and Apple’s promised to eventually open the standard to others, meaning that multiple apps and devices could someday support FaceTime calling. All you’d have to do on a new device is enter your email address, say you’re willing to accept FaceTime calls, and you’d be all set. If Apple plays it correctly, iOS 5 users will be able to call and text each using only data by this time next year, without regard for phone numbers at all. Add in some iChat integration on the desktop and, well, you’ve got the dream.