Popped in my SIM (using a SIM adaptor) and fired it up. Running strong! Don't know how long I'll keep using this, but in light of all the iPhone upgrade talk it's kind of fun to 'downgrade' (from a 6S to this iP4) for a few days. Messages come through and this iPhone seems to be holding a charge equal to my newer iPhone. The bells and whistles are missing, but so far, so good!