If you are visiting from another country, mobile roaming might be expensive. To avoid surprises, check the rates with your local mobile operator before the trip.
Pre-paid sim card
If you plan to be in New York for several days, it makes sense to buy a sim-card from a local mobile operator. The biggest wireless services companies in New York City are AT&T, Verizon and T-Mobile. There are multiple options, some include internet, some don’t. Not all packages include international calls and even incoming sms/text messages.
Here are the options of the pre-paid packages from AT&T (some are just for the calls, others include data):
http://www.att.com/shop/wireless/plans/prepaidplans.html (If you need a zip code, enter hotel’s zip, or just 10001).
If after a trip to New York you go to another city in the United States, your local pre-paid phone will work there with the same rates - the rates are the same throughout the United States and moving to another state will not be considered “roaming”.
If you run out of money in a pre-paid account, you can refill your account in operator’s retail location or online, Please choose “pre-paid/refill account” on the operator’s website.
Tablets
If you need to connect your tablet, for example, an iPad, to the internet in New York, outside of the wi-fi zone, you can purchase a data pass—an alternative of a sim card for tablets.
Here are the options: https://buyasession.att.com/sbd/Common/ShopRatePlans.action.
Please read instructions carefully when you sign up, as some plans get auto-extended and you need to unsubscribe from the service when you don’t need it any longer. Otherwise mobile operator will continue charging your card.