IsatPhone Pro Prepaid Airtime is available in several sizes from as little as 10 units to 5,000 units - unit purchases are valid for 2 years from activation! Physical sim card activated by Explorer Satellite is required initially (free activation). See below for options. All sims are reloadable in the field, remotely, by Explorer Satellite! Not available for use in United States or territories thereof. Please call us for post-paid rates. 1-866-662-2665.