The U.S. Virgin Islands are a part of the North American Numbering Plan (NANP), which allows 20 countries and U.S.-controlled territories to use the same dialing format. However, calls within the NANP are still considered international calls, so higher rates may still apply.

If you are a customer of a major U.S. cellular carrier (such as AT&T, Verizon, or T-Mobile), you generally do not need international calling or a roaming plan for the U.S. Virgin Islands (St. Thomas, St. Croix, and St. John). Because the USVI is a United States territory, most domestic plans treat it as "domestic" coverage, meaning your standard talk, text, and data rates apply just as they would in New York or California. However, there is a very important technical "trap" to be aware of: because of the island's proximity to the British Virgin Islands (BVI), your phone may accidentally "ping" off a tower in Tortola or Jost Van Dyke. If this happens, your phone might enter "International Roaming" mode, leading to expensive per-minute charges. To prevent this, many travelers manually lock their network selection to their home provider in the phone settings or keep "Data Roaming" turned off unless they are sure they are connected to a USVI tower. It is always a good idea to double-check your specific plan's "fine print" before you travel, as some smaller regional carriers or "MVNOs" might still charge a surcharge for off-mainland usage.