Regarding your phone, do note that once you change the billing address to NYC address. You will notice change (increase most likely) on your amount due to taxes.
For example, I opened my mobile phone in NJ with billing address in NJ and when I moved back to NYC for job and updated my billing address. Voila, I started to pay various NYC mobile phone taxes and bill went up from $90 to $100.
Yes, NYC nickles and dimes you to death