Stolen iPhones despite being wiped on US network Verizon still hold iMessage data. "'I can only speculate, but I can see this being plausible," Zdziarski told Ars. 'iMessage registers with the subscriber's phone number from the SIM, so let's say you restore the phone, it will still read the phone number from the SIM. I suppose if you change the SIM out after the phone has been configured, the old number might be cached somewhere either on the phone or on Apple's servers with the UDID of the phone.'

"In other words, iMessage may be pulling the old phone number from a cache somewhere and continuing to use it on the device if the SIM was removed after it was configured as a new phone. We were unable to test this theory (and keep in mind that it's just a theory), but it certainly sounds like one of the more logical explanations for this phenomenon."

One wonders too why Verizon and US carriers don't, like the UK carriers do, block IMEIs of stolen phones. That would stop it too. (Thanks @rquick for the link.)

Ian Fogg's analysis is broad and insightful. There isn't a short version, but equally, it isn't long.

"October 12th, 2011. Mark it down, and come back and yell at me in a few years if I’m wrong. Today is the day SMS begins to die.

"It begins with today’s launch of iOS 5. Or, really, it begins with iMessage."

Actually, this is wrong; SMS is already peaking in a number of western countries, but not because of iMessage, but because of the availability of cheap data plans allied to services such as instant messaging and Twitter and Facebook. Tomi Ahonen has pointed to a peak in SMS in Holland last year. That's before iMessage.