Apple Watch Series 3 (GPS) requires an iPhone 5s or later with iOS 11 or later. Apple Watch Series 3 (GPS + Cellular) requires an iPhone 6 or later with iOS 11 or later. Apple Watch and iPhone service provider must be the same. Cellular is not available with all service providers. Not all service providers support enterprise accounts. Check with your employer and service provider. Some legacy plans may not be compatible. Prepaid plans are not supported. Coverage dependent on carrier network. Roaming is not available outside your carrier network coverage area. Wireless service plan required for cellular service. Contact your service provider for more details.