Automatically joins local network AIS, I get the usual text messages saying welcome to Thailand, get your Vodafone information here etc.
Pretty tired, head to airport hotel. Since phone is set to take the time off the network I don't remember to look, set an alarm to ensure I am up in plenty of time for flight today.
And am woken at 0830 NZ time (0330 local!) because the phone has in fact NOT taken the time from the network and thinks it is still NZ time..!!!
Moral...never assume - check!