Whenever I'm roaming, I often check my bill to make sure that I'm not being charged for anything I shouldn't be. I noticed that last month when I arrived in Spain, my Orange bill showed a text message sent to +447786205094, for which I was charged 10.2p by Orange. I didn't send this text message and there was no record in my iPhone's message history of it having been sent. I then Googled the number and discovered that lots of people around the world have experienced phantom text messages being sent to this number from their iPhones.
It turns out that the iPhone sends a text message to this UK number when FaceTime is activated, and from my own experience, at other times too. While in Spain, I tried deactivating and reactivating Facetime several times, and more outgoing text message charges subsequently appeared on my bill. Apple has programmed iPhones to send a potentially chargeable text to this number without the user's knowledge or consent, which I believe could be an offence by Apple under Section 125 of the Communications Act 2003 or Section 13 of the Theft Act 1968 , which cover making of phone calls without the bill payer's consent.
The many Google results on this subject suggest that iPhone users based in many other countries have similarly been billed for an international text message to this UK mobile number (belonging apparently to Vodafone). It seems that all iPhones globally use this same UK number for FaceTime activation. Because UK iPhone tariffs typically provide inclusive text messages within the UK, very few UK iPhone users have noticed this problem; however, it is always apparent when roaming. Other networks around the world have apparently configured their billing systems not to charge for text messages to +447786205094 to avoid their customers being charged unexpectedly for international text messages.