I'm not sure what messages you refer to? You don't need a SIM card to activate either, you can just use wifi or itunes. An iPhone SE without a SIM is basically identical to a 6th-gen iPod Touch in functionality.
I'm going to Japan in a few months and plan on picking up a data SIM at the airport for my phone, free/public wifi coverage is less common than here.
I'm going to Japan in a few months and plan on picking up a data SIM at the airport for my phone, free/public wifi coverage is less common than here.