Yesterday morning I had a video conference with Bangkok, as international men of mystery like myself do on Friday mornings. It was actually with my friend Jacob, who is there for a month on business and had his workday cancelled because of the heavy flooding Thailand is currently experiencing, so he was bored in his hotel suite and sent me an iMessage. When I initiated a FaceTime call with him, I realized as soon a I pressed the button to call him that there was no way it would work. To explain why, I have to tell you a bit about his current phone situation. His employer bought him an a iPhone 4 with Verizon soon after they released the CDMA version of the iPhone 4. It worked well, but wouldn't work abroad, since the rest of the planet uses GSM cellular networks. For whatever reason, they decided to solve this problem by buying him an Android phone, letting him keep his iPhone 4, but without the sim card, thus converting it more or less into an iPod Touch.
What I realized when I attempted to initiate a FaceTime call with him this morning was that I was calling his phone number with FaceTime, which is now assigned to the 'droid. So you can imagine my surprise when he answered and grinned at me. What the heck just happened?
My phone contacted Apple's main servers asking them to find a device that was registered with his phone number. His iPhone had either been marked with his phone number or knew that phone number belonged to the address book entry corresponding to the owner of the phone, and had registered with Apple's servers as soon as it had connected to his hotel wifi. Thus my phone was able to find and communicate with his phone. Amazing.
The story Jacob told me from his previous day at work amazed me even more. For whatever reason, he had needed to send a text message to a colleague who had an iPhone. iOS5's new iMessage messaging service slipped his mind, so he assumed he'd need to use his 'droid to send the message. He sent it, and his colleague's phone beeped when it received the message. But then something odd happened. Jacob's iPhone beeped too! There in his messaging application was a sent message from himself to his colleague, the beginning of an iMessage chat conversation. What happened!?
His colleague's iPhone received the message and registered a message received from Jacob's phone number to the iCloud servers. The iCloud servers recognized the number as belonging to Jacob's iPhone, which was connected only to wifi, and pushed the message down to his phone as if he had sent it from the iPhone. Unbelievable!
I expect to have many more "How did it know to do that??" moments as I continue to use iCloud to synchronize all my iDevices.